1
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Huai S, Bu K, Gu X, Zhang Z, An S, Yang X, Li Y, Cai T, Zheng Y. Fast joint parity measurement via collective interactions induced by stimulated emission. Nat Commun 2024; 15:3045. [PMID: 38589424 PMCID: PMC11001884 DOI: 10.1038/s41467-024-47379-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 03/29/2024] [Indexed: 04/10/2024] Open
Abstract
Parity detection is essential in quantum error correction. Error syndromes coded in parity are detected routinely by sequential CNOT gates. Here, different from the standard CNOT-gate based scheme, we propose a reliable joint parity measurement (JPM) scheme inspired by stimulated emission. By controlling the collective behavior between data qubits and syndrome qubit, we realize the parity detection and experimentally implement the weight-2 and weight-4 JPM scheme in a tunable coupling superconducting circuit, which shows comparable performance to the CNOT scheme. Moreover, with the aid of the coupling tunability in quantum system, this scheme can be further utilized for specific joint entangling state preparation (JEP) with high fidelity, such as multiqubit entangled state preparation for non-adjacent qubits. This strategy, combined with the superconducting qubit system with tunable couplers, reveals tremendous potential and applications in the surface code architecture without adding extra circuit elements. Besides, the method we develop here can readily be applied in large-scale quantum computation and quantum simulation.
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Affiliation(s)
- Sainan Huai
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Kunliang Bu
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Xiu Gu
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China.
| | - Zhenxing Zhang
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Shuoming An
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Xiaopei Yang
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Yuan Li
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Tianqi Cai
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China.
| | - Yicong Zheng
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
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2
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Mori Y, Kawabata S, Matsuzaki Y. How to experimentally evaluate the adiabatic condition for quantum annealing. Sci Rep 2024; 14:8177. [PMID: 38589470 PMCID: PMC11001971 DOI: 10.1038/s41598-024-58286-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 03/27/2024] [Indexed: 04/10/2024] Open
Abstract
We propose an experimental method for evaluating the adiabatic condition during quantum annealing (QA), which will be essential for solving practical problems. The adiabatic condition consists of the transition matrix element and the energy gap, and our method simultaneously provides information about these components without diagonalizing the Hamiltonian. The key idea is to measure the power spectrum of a time domain signal by adding an oscillating field during QA, and we can estimate the values of the transition matrix element and energy gap from the measurement output. Our results provides a powerful experimental basis for analyzing the performance of QA.
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Affiliation(s)
- Yuichiro Mori
- Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
| | - Shiro Kawabata
- Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
- NEC-AIST Quantum Technology Cooperative Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8568, Japan.
| | - Yuichiro Matsuzaki
- Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
- NEC-AIST Quantum Technology Cooperative Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8568, Japan.
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3
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Eriksson AM, Sépulcre T, Kervinen M, Hillmann T, Kudra M, Dupouy S, Lu Y, Khanahmadi M, Yang J, Castillo-Moreno C, Delsing P, Gasparinetti S. Universal control of a bosonic mode via drive-activated native cubic interactions. Nat Commun 2024; 15:2512. [PMID: 38509084 PMCID: PMC10954688 DOI: 10.1038/s41467-024-46507-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
Linear bosonic modes offer a hardware-efficient alternative for quantum information processing but require access to some nonlinearity for universal control. The lack of nonlinearity in photonics has led to encoded measurement-based quantum computing, which relies on linear operations but requires access to resourceful ('nonlinear') quantum states, such as cubic phase states. In contrast, superconducting microwave circuits offer engineerable nonlinearities but suffer from static Kerr nonlinearity. Here, we demonstrate universal control of a bosonic mode composed of a superconducting nonlinear asymmetric inductive element (SNAIL) resonator, enabled by native nonlinearities in the SNAIL element. We suppress static nonlinearities by operating the SNAIL in the vicinity of its Kerr-free point and dynamically activate nonlinearities up to third order by fast flux pulses. We experimentally realize a universal set of generalized squeezing operations, as well as the cubic phase gate, and exploit them to deterministically prepare a cubic phase state in 60 ns. Our results initiate the experimental field of polynomial quantum computing, in the continuous-variables notion originally introduced by Lloyd and Braunstein.
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Affiliation(s)
- Axel M Eriksson
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
| | - Théo Sépulcre
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Mikael Kervinen
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Timo Hillmann
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Marina Kudra
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Simon Dupouy
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Yong Lu
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
- Physikalisches Institut, University of Stuttgart, 70569, Stuttgart, Germany
| | - Maryam Khanahmadi
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Jiaying Yang
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Claudia Castillo-Moreno
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden
| | - Simone Gasparinetti
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
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4
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Klimov PV, Bengtsson A, Quintana C, Bourassa A, Hong S, Dunsworth A, Satzinger KJ, Livingston WP, Sivak V, Niu MY, Andersen TI, Zhang Y, Chik D, Chen Z, Neill C, Erickson C, Grajales Dau A, Megrant A, Roushan P, Korotkov AN, Kelly J, Smelyanskiy V, Chen Y, Neven H. Optimizing quantum gates towards the scale of logical qubits. Nat Commun 2024; 15:2442. [PMID: 38499541 PMCID: PMC10948820 DOI: 10.1038/s41467-024-46623-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 03/04/2024] [Indexed: 03/20/2024] Open
Abstract
A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high-performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dynamic control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by ~3.7× compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Alexander N Korotkov
- Google AI, Mountain View, CA, USA
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, USA
| | | | | | - Yu Chen
- Google AI, Mountain View, CA, USA
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5
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Gil-Fuster E, Eisert J, Bravo-Prieto C. Understanding quantum machine learning also requires rethinking generalization. Nat Commun 2024; 15:2277. [PMID: 38480684 PMCID: PMC10938005 DOI: 10.1038/s41467-024-45882-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 02/06/2024] [Indexed: 03/17/2024] Open
Abstract
Quantum machine learning models have shown successful generalization performance even when trained with few data. In this work, through systematic randomization experiments, we show that traditional approaches to understanding generalization fail to explain the behavior of such quantum models. Our experiments reveal that state-of-the-art quantum neural networks accurately fit random states and random labeling of training data. This ability to memorize random data defies current notions of small generalization error, problematizing approaches that build on complexity measures such as the VC dimension, the Rademacher complexity, and all their uniform relatives. We complement our empirical results with a theoretical construction showing that quantum neural networks can fit arbitrary labels to quantum states, hinting at their memorization ability. Our results do not preclude the possibility of good generalization with few training data but rather rule out any possible guarantees based only on the properties of the model family. These findings expose a fundamental challenge in the conventional understanding of generalization in quantum machine learning and highlight the need for a paradigm shift in the study of quantum models for machine learning tasks.
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Affiliation(s)
- Elies Gil-Fuster
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Berlin, Germany
- Fraunhofer Heinrich Hertz Institute, Berlin, Germany
| | - Jens Eisert
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Berlin, Germany.
- Fraunhofer Heinrich Hertz Institute, Berlin, Germany.
- Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
| | - Carlos Bravo-Prieto
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Berlin, Germany.
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6
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Jain S, Sägesser T, Hrmo P, Torkzaban C, Stadler M, Oswald R, Axline C, Bautista-Salvador A, Ospelkaus C, Kienzler D, Home J. Penning micro-trap for quantum computing. Nature 2024; 627:510-514. [PMID: 38480890 PMCID: PMC10954548 DOI: 10.1038/s41586-024-07111-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 01/24/2024] [Indexed: 03/18/2024]
Abstract
Trapped ions in radio-frequency traps are among the leading approaches for realizing quantum computers, because of high-fidelity quantum gates and long coherence times1-3. However, the use of radio-frequencies presents several challenges to scaling, including requiring compatibility of chips with high voltages4, managing power dissipation5 and restricting transport and placement of ions6. Here we realize a micro-fabricated Penning ion trap that removes these restrictions by replacing the radio-frequency field with a 3 T magnetic field. We demonstrate full quantum control of an ion in this setting, as well as the ability to transport the ion arbitrarily in the trapping plane above the chip. This unique feature of the Penning micro-trap approach opens up a modification of the quantum charge-coupled device architecture with improved connectivity and flexibility, facilitating the realization of large-scale trapped-ion quantum computing, quantum simulation and quantum sensing.
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Affiliation(s)
- Shreyans Jain
- Department of Physics, ETH Zürich, Zurich, Switzerland.
- Quantum Center, ETH Zürich, Zurich, Switzerland.
| | - Tobias Sägesser
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
| | - Pavel Hrmo
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
| | | | - Martin Stadler
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
| | - Robin Oswald
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
| | - Chris Axline
- Department of Physics, ETH Zürich, Zurich, Switzerland
| | - Amado Bautista-Salvador
- Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
| | - Christian Ospelkaus
- Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
| | - Daniel Kienzler
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
| | - Jonathan Home
- Department of Physics, ETH Zürich, Zurich, Switzerland
- Quantum Center, ETH Zürich, Zurich, Switzerland
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7
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Huang JY, Su RY, Lim WH, Feng M, van Straaten B, Severin B, Gilbert W, Dumoulin Stuyck N, Tanttu T, Serrano S, Cifuentes JD, Hansen I, Seedhouse AE, Vahapoglu E, Leon RCC, Abrosimov NV, Pohl HJ, Thewalt MLW, Hudson FE, Escott CC, Ares N, Bartlett SD, Morello A, Saraiva A, Laucht A, Dzurak AS, Yang CH. High-fidelity spin qubit operation and algorithmic initialization above 1 K. Nature 2024; 627:772-777. [PMID: 38538941 PMCID: PMC10972758 DOI: 10.1038/s41586-024-07160-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 02/05/2024] [Indexed: 04/01/2024]
Abstract
The encoding of qubits in semiconductor spin carriers has been recognized as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale1-10. However, the operation of the large number of qubits required for advantageous quantum applications11-13 will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 K, at which the cooling power is orders of magnitude higher14-18. Here we tune up and operate spin qubits in silicon above 1 K, with fidelities in the range required for fault-tolerant operations at these temperatures19-21. We design an algorithmic initialization protocol to prepare a pure two-qubit state even when the thermal energy is substantially above the qubit energies and incorporate radiofrequency readout to achieve fidelities up to 99.34% for both readout and initialization. We also demonstrate single-qubit Clifford gate fidelities up to 99.85% and a two-qubit gate fidelity of 98.92%. These advances overcome the fundamental limitation that the thermal energy must be well below the qubit energies for the high-fidelity operation to be possible, surmounting a main obstacle in the pathway to scalable and fault-tolerant quantum computation.
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Affiliation(s)
- Jonathan Y Huang
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
| | - Rocky Y Su
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Wee Han Lim
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - MengKe Feng
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | | | - Brandon Severin
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Will Gilbert
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Nard Dumoulin Stuyck
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Tuomo Tanttu
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Santiago Serrano
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Jesus D Cifuentes
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Ingvild Hansen
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Amanda E Seedhouse
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Ensar Vahapoglu
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Ross C C Leon
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Quantum Motion Technologies, London, UK
| | | | | | - Michael L W Thewalt
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Fay E Hudson
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Christopher C Escott
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Natalia Ares
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Stephen D Bartlett
- Centre for Engineered Quantum Systems, School of Physics, University of Sydney, Sydney, New South Wales, Australia
| | - Andrea Morello
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
| | - Andre Saraiva
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia
- Diraq, Sydney, New South Wales, Australia
| | - Andrew S Dzurak
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
- Diraq, Sydney, New South Wales, Australia.
| | - Chih Hwan Yang
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales, Australia.
- Diraq, Sydney, New South Wales, Australia.
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8
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Li Z, Roy T, Rodríguez Pérez D, Lee KH, Kapit E, Schuster DI. Autonomous error correction of a single logical qubit using two transmons. Nat Commun 2024; 15:1681. [PMID: 38395989 PMCID: PMC10891116 DOI: 10.1038/s41467-024-45858-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Large-scale quantum computers will inevitably need quantum error correction to protect information against decoherence. Traditional error correction typically requires many qubits, along with high-efficiency error syndrome measurement and real-time feedback. Autonomous quantum error correction instead uses steady-state bath engineering to perform the correction in a hardware-efficient manner. In this work, we develop a new autonomous quantum error correction scheme that actively corrects single-photon loss and passively suppresses low-frequency dephasing, and we demonstrate an important experimental step towards its full implementation with transmons. Compared to uncorrected encoding, improvements are experimentally witnessed for the logical zero, one, and superposition states. Our results show the potential of implementing hardware-efficient autonomous quantum error correction to enhance the reliability of a transmon-based quantum information processor.
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Affiliation(s)
- Ziqian Li
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
- Department of Physics, University of Chicago, Chicago, IL, 60637, USA
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA
| | - Tanay Roy
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
- Department of Physics, University of Chicago, Chicago, IL, 60637, USA
| | | | - Kan-Heng Lee
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
- Department of Physics, University of Chicago, Chicago, IL, 60637, USA
| | - Eliot Kapit
- Department of Physics, Colorado School of Mines, Golden, CO, 80401, USA
| | - David I Schuster
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.
- Department of Physics, University of Chicago, Chicago, IL, 60637, USA.
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA.
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9
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Berritta F, Rasmussen T, Krzywda JA, van der Heijden J, Fedele F, Fallahi S, Gardner GC, Manfra MJ, van Nieuwenburg E, Danon J, Chatterjee A, Kuemmeth F. Real-time two-axis control of a spin qubit. Nat Commun 2024; 15:1676. [PMID: 38395978 PMCID: PMC10891052 DOI: 10.1038/s41467-024-45857-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Optimal control of qubits requires the ability to adapt continuously to their ever-changing environment. We demonstrate a real-time control protocol for a two-electron singlet-triplet qubit with two fluctuating Hamiltonian parameters. Our approach leverages single-shot readout classification and dynamic waveform generation, allowing full Hamiltonian estimation to dynamically stabilize and optimize the qubit performance. Powered by a field-programmable gate array (FPGA), the quantum control electronics estimates the Overhauser field gradient between the two electrons in real time, enabling controlled Overhauser-driven spin rotations and thus bypassing the need for micromagnets or nuclear polarization protocols. It also estimates the exchange interaction between the two electrons and adjusts their detuning, resulting in extended coherence of Hadamard rotations when correcting for fluctuations of both qubit axes. Our study highlights the role of feedback in enhancing the performance and stability of quantum devices affected by quasistatic noise.
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Affiliation(s)
- Fabrizio Berritta
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark.
| | - Torbjørn Rasmussen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Jan A Krzywda
- Lorentz Institute and Leiden Institute of Advanced Computer Science, Leiden University, P.O. Box 9506, 2300 RA, Leiden, The Netherlands
| | | | - Federico Fedele
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Saeed Fallahi
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Geoffrey C Gardner
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Michael J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
- School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Evert van Nieuwenburg
- Lorentz Institute and Leiden Institute of Advanced Computer Science, Leiden University, P.O. Box 9506, 2300 RA, Leiden, The Netherlands
| | - Jeroen Danon
- Department of Physics, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Anasua Chatterjee
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark.
| | - Ferdinand Kuemmeth
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark.
- QDevil, Quantum Machines, 2750, Ballerup, Denmark.
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10
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Struck T, Volmer M, Visser L, Offermann T, Xue R, Tu JS, Trellenkamp S, Cywiński Ł, Bluhm H, Schreiber LR. Spin-EPR-pair separation by conveyor-mode single electron shuttling in Si/SiGe. Nat Commun 2024; 15:1325. [PMID: 38351007 PMCID: PMC10864332 DOI: 10.1038/s41467-024-45583-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/29/2024] [Indexed: 02/16/2024] Open
Abstract
Long-ranged coherent qubit coupling is a missing function block for scaling up spin qubit based quantum computing solutions. Spin-coherent conveyor-mode electron-shuttling could enable spin quantum-chips with scalable and sparse qubit-architecture. Its key feature is the operation by only few easily tuneable input terminals and compatibility with industrial gate-fabrication. Single electron shuttling in conveyor-mode in a 420 nm long quantum bus has been demonstrated previously. Here we investigate the spin coherence during conveyor-mode shuttling by separation and rejoining an Einstein-Podolsky-Rosen (EPR) spin-pair. Compared to previous work we boost the shuttle velocity by a factor of 10000. We observe a rising spin-qubit dephasing time with the longer shuttle distances due to motional narrowing and estimate the spin-shuttle infidelity due to dephasing to be 0.7% for a total shuttle distance of nominal 560 nm. Shuttling several loops up to an accumulated distance of 3.36 μm, spin-entanglement of the EPR pair is still detectable, giving good perspective for our approach of a shuttle-based scalable quantum computing architecture in silicon.
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Affiliation(s)
- Tom Struck
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Mats Volmer
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Lino Visser
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Tobias Offermann
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Ran Xue
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Jhih-Sian Tu
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility (HNF), Forschungszentrum Jülich, Jülich, Germany
| | - Łukasz Cywiński
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Hendrik Bluhm
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
- ARQUE Systems GmbH, Aachen, Germany
| | - Lars R Schreiber
- JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany.
- ARQUE Systems GmbH, Aachen, Germany.
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11
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Ungerer JH, Pally A, Kononov A, Lehmann S, Ridderbos J, Potts PP, Thelander C, Dick KA, Maisi VF, Scarlino P, Baumgartner A, Schönenberger C. Strong coupling between a microwave photon and a singlet-triplet qubit. Nat Commun 2024; 15:1068. [PMID: 38316779 PMCID: PMC10844229 DOI: 10.1038/s41467-024-45235-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/18/2024] [Indexed: 02/07/2024] Open
Abstract
Combining superconducting resonators and quantum dots has triggered tremendous progress in quantum information, however, attempts at coupling a resonator to even charge parity spin qubits have resulted only in weak spin-photon coupling. Here, we integrate a zincblende InAs nanowire double quantum dot with strong spin-orbit interaction in a magnetic-field resilient, high-quality resonator. The quantum confinement in the nanowire is achieved using deterministically grown wurtzite tunnel barriers. Our experiments on even charge parity states and at large magnetic fields, allow us to identify the relevant spin states and to measure the spin decoherence rates and spin-photon coupling strengths. We find an anti-crossing between the resonator mode in the single photon limit and a singlet-triplet qubit with a spin-photon coupling strength of g/2π = 139 ± 4 MHz. This coherent coupling exceeds the resonator decay rate κ/2π = 19.8 ± 0.2 MHz and the qubit dephasing rate γ/2π = 116 ± 7 MHz, putting our system in the strong coupling regime.
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Affiliation(s)
- J H Ungerer
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
| | - A Pally
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
| | - A Kononov
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - S Lehmann
- Solid State Physics and NanoLund, Lund University, Box 118, S-22100, Lund, Sweden
| | - J Ridderbos
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - P P Potts
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - C Thelander
- Solid State Physics and NanoLund, Lund University, Box 118, S-22100, Lund, Sweden
| | - K A Dick
- Centre for Analysis and Synthesis, Lund University, Box 124, S-22100, Lund, Sweden
| | - V F Maisi
- Solid State Physics and NanoLund, Lund University, Box 118, S-22100, Lund, Sweden
| | - P Scarlino
- Institute of Physics and Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - A Baumgartner
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - C Schönenberger
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
- Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
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12
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Bluvstein D, Evered SJ, Geim AA, Li SH, Zhou H, Manovitz T, Ebadi S, Cain M, Kalinowski M, Hangleiter D, Bonilla Ataides JP, Maskara N, Cong I, Gao X, Sales Rodriguez P, Karolyshyn T, Semeghini G, Gullans MJ, Greiner M, Vuletić V, Lukin MD. Logical quantum processor based on reconfigurable atom arrays. Nature 2024; 626:58-65. [PMID: 38056497 PMCID: PMC10830422 DOI: 10.1038/s41586-023-06927-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 12/01/2023] [Indexed: 12/08/2023]
Abstract
Suppressing errors is the central challenge for useful quantum computing1, requiring quantum error correction (QEC)2-6 for large-scale processing. However, the overhead in the realization of error-corrected 'logical' qubits, in which information is encoded across many physical qubits for redundancy2-4, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays7, our system combines high two-qubit gate fidelities8, arbitrary connectivity7,9, as well as fully programmable single-qubit rotations and mid-circuit readout10-15. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code6 distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities5, fault-tolerant creation of logical Greenberger-Horne-Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks16,17, we realize computationally complex sampling circuits18 with up to 48 logical qubits entangled with hypercube connectivity19 with 228 logical two-qubit gates and 48 logical CCZ gates20. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling21,22. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.
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Affiliation(s)
- Dolev Bluvstein
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Simon J Evered
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Sophie H Li
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Hengyun Zhou
- Department of Physics, Harvard University, Cambridge, MA, USA
- QuEra Computing Inc., Boston, MA, USA
| | - Tom Manovitz
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Sepehr Ebadi
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Madelyn Cain
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Dominik Hangleiter
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, MD, USA
| | | | - Nishad Maskara
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Iris Cong
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Xun Gao
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | | | - Giulia Semeghini
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Michael J Gullans
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, MD, USA
| | - Markus Greiner
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Vladan Vuletić
- Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mikhail D Lukin
- Department of Physics, Harvard University, Cambridge, MA, USA.
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13
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Lopez-Bezanilla A, King AD, Nisoli C, Saxena A. Quantum fluctuations drive nonmonotonic correlations in a qubit lattice. Nat Commun 2024; 15:589. [PMID: 38238310 PMCID: PMC10796911 DOI: 10.1038/s41467-023-44281-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 12/06/2023] [Indexed: 01/22/2024] Open
Abstract
Fluctuations may induce the degradation of order by overcoming ordering interactions, consequently leading to an increase of entropy. This is particularly evident in magnetic systems characterized by nontrivial, constrained disorder, where thermal or quantum fluctuations can yield counterintuitive forms of ordering. Using the proven efficiency of quantum annealers as programmable spin system simulators, we present a study based on entropy postulates and experiments on a platform of programmable superconducting qubits to show that a low level of uncertainty can promote ordering in a system impacted by both thermal and quantum fluctuations. A set of experiments is proposed on a lattice of interacting qubits arranged in a triangular geometry with precisely controlled disorder, effective temperature, and quantum fluctuations. Our results demonstrate the creation of ordered ferrimagnetic and layered anisotropic disordered phases, displaying characteristics akin to the elegant order-by-disorder phenomenon. Extensive experimental evidence is provided for the role of quantum fluctuations in lowering the total energy of the system by increasing entropy and defect clustering. Our thorough and comprehensive application of an intentionally introduced noise on a quantum platform provides insight into the dynamics of defects and fluctuations in quantum devices, which may help to reduce the cost associated with quantum processing.
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Affiliation(s)
| | | | - Cristiano Nisoli
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
| | - Avadh Saxena
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, 87545, NM, USA
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14
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Mehdi E, Gundín M, Millet C, Somaschi N, Lemaître A, Sagnes I, Le Gratiet L, Fioretto DA, Belabas N, Krebs O, Senellart P, Lanco L. Giant optical polarisation rotations induced by a single quantum dot spin. Nat Commun 2024; 15:598. [PMID: 38238312 PMCID: PMC10796934 DOI: 10.1038/s41467-023-44651-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 12/27/2023] [Indexed: 01/22/2024] Open
Abstract
In the framework of optical quantum computing and communications, a major objective consists in building receiving nodes implementing conditional operations on incoming photons, using a single stationary qubit. In particular, the quest for scalable nodes motivated the development of cavity-enhanced spin-photon interfaces with solid-state emitters. An important challenge remains, however, to produce a stable, controllable, spin-dependent photon state, in a deterministic way. Here we use an electrically-contacted pillar-based cavity, embedding a single InGaAs quantum dot, to demonstrate giant polarisation rotations induced on reflected photons by a single electron spin. A complete tomography approach is introduced to extrapolate the output polarisation Stokes vector, conditioned by a specific spin state, in presence of spin and charge fluctuations. We experimentally approach polarisation states conditionally rotated by [Formula: see text], π, and [Formula: see text] in the Poincaré sphere with extrapolated fidelities of (97 ± 1) %, (84 ± 7) %, and (90 ± 8) %, respectively. We find that an enhanced light-matter coupling, together with limited cavity birefringence and reduced spectral fluctuations, allow targeting most conditional rotations in the Poincaré sphere, with a control both in longitude and latitude. Such polarisation control may prove crucial to adapt spin-photon interfaces to various configurations and protocols for quantum information.
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Affiliation(s)
- E Mehdi
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
- Université Paris Cité, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - M Gundín
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - C Millet
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - N Somaschi
- Quandela, 7 rue Leonard de Vinci, 91300, Massy, France
| | - A Lemaître
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - I Sagnes
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - L Le Gratiet
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - D A Fioretto
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
- Quandela, 7 rue Leonard de Vinci, 91300, Massy, France
| | - N Belabas
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - O Krebs
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - P Senellart
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France
| | - L Lanco
- Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
- Université Paris Cité, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
- Institut Universitaire de France (IUF), 75005, Paris, France.
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15
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Liu J, Liu M, Liu JP, Ye Z, Wang Y, Alexeev Y, Eisert J, Jiang L. Towards provably efficient quantum algorithms for large-scale machine-learning models. Nat Commun 2024; 15:434. [PMID: 38199993 PMCID: PMC10781664 DOI: 10.1038/s41467-023-43957-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 11/24/2023] [Indexed: 01/12/2024] Open
Abstract
Large machine learning models are revolutionary technologies of artificial intelligence whose bottlenecks include huge computational expenses, power, and time used both in the pre-training and fine-tuning process. In this work, we show that fault-tolerant quantum computing could possibly provide provably efficient resolutions for generic (stochastic) gradient descent algorithms, scaling as [Formula: see text], where n is the size of the models and T is the number of iterations in the training, as long as the models are both sufficiently dissipative and sparse, with small learning rates. Based on earlier efficient quantum algorithms for dissipative differential equations, we find and prove that similar algorithms work for (stochastic) gradient descent, the primary algorithm for machine learning. In practice, we benchmark instances of large machine learning models from 7 million to 103 million parameters. We find that, in the context of sparse training, a quantum enhancement is possible at the early stage of learning after model pruning, motivating a sparse parameter download and re-upload scheme. Our work shows solidly that fault-tolerant quantum algorithms could potentially contribute to most state-of-the-art, large-scale machine-learning problems.
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Affiliation(s)
- Junyu Liu
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, 60637, USA
- Department of Computer Science, The University of Chicago, Chicago, IL, 60637, USA
- Chicago Quantum Exchange, Chicago, IL, 60637, USA
- Kadanoff Center for Theoretical Physics, The University of Chicago, Chicago, IL, 60637, USA
- qBraid Co., Chicago, IL, 60615, USA
- SeQure, Chicago, IL, 60615, USA
| | - Minzhao Liu
- Department of Physics, The University of Chicago, Chicago, IL, 60637, USA
- Computational Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Jin-Peng Liu
- Simons Institute for the Theory of Computing, University of California, Berkeley, CA, 94720, USA
- Department of Mathematics, University of California, Berkeley, CA, 94720, USA
- Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ziyu Ye
- Department of Computer Science, The University of Chicago, Chicago, IL, 60637, USA
| | - Yunfei Wang
- Martin A. Fisher School of Physics, Brandeis University, Waltham, MA, 02453, USA
| | - Yuri Alexeev
- Department of Computer Science, The University of Chicago, Chicago, IL, 60637, USA
- Chicago Quantum Exchange, Chicago, IL, 60637, USA
- Computational Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Jens Eisert
- Dahlem Center for Complex Quantum Systems, Free University Berlin, Berlin, 14195, Germany.
| | - Liang Jiang
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, 60637, USA
- Chicago Quantum Exchange, Chicago, IL, 60637, USA
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16
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Ahn B, Park J, Lee J, Lee S. High-dimensional single photon based quantum secure direct communication using time and phase mode degrees. Sci Rep 2024; 14:888. [PMID: 38195695 PMCID: PMC10776589 DOI: 10.1038/s41598-024-51212-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/02/2024] [Indexed: 01/11/2024] Open
Abstract
Quantum secure direct communication (QSDC) can guarantee security using the characteristics of quantum mechanics even when a message is directly transmitted through a quantum channel without using a secret key. However, the transmission rate of the QSDC is limited by the dead time of a single photon detector (SPD) as well as channel loss over the distance. To overcome this limited transmission rate, we propose a high-dimensional single photon-based QSDC protocol that applies two optical degrees of freedom: time and phase state. First, an N-dimensional time and phase state generation method that considers the dead time is proposed to minimize the measurement loss of a transmitted message. Second, among the two types of quantum states, the phase state with relatively low measurement efficiency is used only for eavesdropping detection, and the time state is used for sending messages with differential delay time bin-based encoding techniques. Lastly, we propose an efficient method for measuring N-dimensional time and phase-based quantum states and recovering classical bit information. This study performs security analysis against various attacks, and verifies the transmission rate improvement effect through simulation. The result indicates that our proposal can guarantee higher security and transmission rates compared to the conventional DL04 QSDC.
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Affiliation(s)
- Byungkyu Ahn
- Communication and Media Standard Lab., LG Electronics, Seoul, 06772, South Korea.
| | - Jooyoun Park
- Communication and Media Standard Lab., LG Electronics, Seoul, 06772, South Korea
| | - Jonghyun Lee
- Communication and Media Standard Lab., LG Electronics, Seoul, 06772, South Korea
| | - Sangrim Lee
- Communication and Media Standard Lab., LG Electronics, Seoul, 06772, South Korea
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17
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Gu A, Cincio L, Coles PJ. Practical Hamiltonian learning with unitary dynamics and Gibbs states. Nat Commun 2024; 15:312. [PMID: 38191523 PMCID: PMC10774402 DOI: 10.1038/s41467-023-44008-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 11/24/2023] [Indexed: 01/10/2024] Open
Abstract
We study the problem of learning the parameters for the Hamiltonian of a quantum many-body system, given limited access to the system. In this work, we build upon recent approaches to Hamiltonian learning via derivative estimation. We propose a protocol that improves the scaling dependence of prior works, particularly with respect to parameters relating to the structure of the Hamiltonian (e.g., its locality k). Furthermore, by deriving exact bounds on the performance of our protocol, we are able to provide a precise numerical prescription for theoretically optimal settings of hyperparameters in our learning protocol, such as the maximum evolution time (when learning with unitary dynamics) or minimum temperature (when learning with Gibbs states). Thanks to these improvements, our protocol has practical scaling for large problems: we demonstrate this with a numerical simulation of our protocol on an 80-qubit system.
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Affiliation(s)
- Andi Gu
- Department of Physics, University of California, Berkeley, Berkeley, CA, USA.
- Harvard Quantum Initiative, Harvard University, Cambridge, MA, 02138, USA.
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
| | - Lukasz Cincio
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Patrick J Coles
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Normal Computing Corporation, New York, NY, USA
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18
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Feng L, Huang YY, Wu YK, Guo WX, Ma JY, Yang HX, Zhang L, Wang Y, Huang CX, Zhang C, Yao L, Qi BX, Pu YF, Zhou ZC, Duan LM. Realization of a crosstalk-avoided quantum network node using dual-type qubits of the same ion species. Nat Commun 2024; 15:204. [PMID: 38172118 PMCID: PMC10764850 DOI: 10.1038/s41467-023-44220-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
Generating ion-photon entanglement is a crucial step for scalable trapped-ion quantum networks. To avoid the crosstalk on memory qubits carrying quantum information, it is common to use a different ion species for ion-photon entanglement generation such that the scattered photons are far off-resonant for the memory qubits. However, such a dual-species scheme can be subject to inefficient sympathetic cooling due to the mass mismatch of the ions. Here we demonstrate a trapped-ion quantum network node in the dual-type qubit scheme where two types of qubits are encoded in the S and F hyperfine structure levels of 171Yb+ ions. We generate ion photon entanglement for the S-qubit in a typical timescale of hundreds of milliseconds, and verify its small crosstalk on a nearby F-qubit with coherence time above seconds. Our work demonstrates an enabling function of the dual-type qubit scheme for scalable quantum networks.
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Affiliation(s)
- L Feng
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - Y-Y Huang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
- Hefei National Laboratory, Hefei, 230088, PR China
| | - W-X Guo
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
- HYQ Co. Ltd., Beijing, 100176, PR China
| | - J-Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
- HYQ Co. Ltd., Beijing, 100176, PR China
| | - H-X Yang
- HYQ Co. Ltd., Beijing, 100176, PR China
| | - L Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - Y Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - C-X Huang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - C Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - L Yao
- HYQ Co. Ltd., Beijing, 100176, PR China
| | - B-X Qi
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
| | - Y-F Pu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
- Hefei National Laboratory, Hefei, 230088, PR China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China
- Hefei National Laboratory, Hefei, 230088, PR China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, PR China.
- Hefei National Laboratory, Hefei, 230088, PR China.
- New Cornerstone Science Laboratory, Beijing, 100084, PR China.
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19
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Iyama D, Kamiya T, Fujii S, Mukai H, Zhou Y, Nagase T, Tomonaga A, Wang R, Xue JJ, Watabe S, Kwon S, Tsai JS. Observation and manipulation of quantum interference in a superconducting Kerr parametric oscillator. Nat Commun 2024; 15:86. [PMID: 38167480 PMCID: PMC10762009 DOI: 10.1038/s41467-023-44496-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024] Open
Abstract
Quantum tunneling is the phenomenon that makes superconducting circuits "quantum". Recently, there has been a renewed interest in using quantum tunneling in phase space of a Kerr parametric oscillator as a resource for quantum information processing. Here, we report a direct observation of quantum interference induced by such tunneling and its dynamics in a planar superconducting circuit through Wigner tomography. We experimentally elucidate all essential properties of this quantum interference, such as mapping from Fock states to cat states, a temporal oscillation due to the pump detuning, as well as its characteristic Rabi oscillations and Ramsey fringes. Finally, we perform gate operations as manipulations of the observed quantum interference. Our findings lay the groundwork for further studies on quantum properties of superconducting Kerr parametric oscillators and their use in quantum information technologies.
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Affiliation(s)
- Daisuke Iyama
- Department of Physics, Graduate School of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
| | - Takahiko Kamiya
- Department of Physics, Graduate School of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
| | - Shiori Fujii
- Department of Physics, Graduate School of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
| | - Hiroto Mukai
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
- Research Institute for Science and Technology, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
| | - Yu Zhou
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
| | - Toshiaki Nagase
- Department of Physics, Graduate School of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
| | - Akiyoshi Tomonaga
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
- Research Institute for Science and Technology, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
| | - Rui Wang
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
- Research Institute for Science and Technology, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
| | - Jiao-Jiao Xue
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
- Institute of Theoretical Physics, School of Physics, Xi'an Jiaotong University, Xi'an, People's Republic of China
| | - Shohei Watabe
- College of Engineering, Department of Computer Science and Engineering, Shibaura Institute of Technology, Koto-ku, Tokyo, Japan
| | - Sangil Kwon
- Research Institute for Science and Technology, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan.
| | - Jaw-Shen Tsai
- RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama, Japan
- Research Institute for Science and Technology, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
- Graduate School of Science, Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
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20
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Gong R, Du X, Janzen E, Liu V, Liu Z, He G, Ye B, Li T, Yao NY, Edgar JH, Henriksen EA, Zu C. Isotope engineering for spin defects in van der Waals materials. Nat Commun 2024; 15:104. [PMID: 38168074 PMCID: PMC10761865 DOI: 10.1038/s41467-023-44494-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024] Open
Abstract
Spin defects in van der Waals materials offer a promising platform for advancing quantum technologies. Here, we propose and demonstrate a powerful technique based on isotope engineering of host materials to significantly enhance the coherence properties of embedded spin defects. Focusing on the recently-discovered negatively charged boron vacancy center ([Formula: see text]) in hexagonal boron nitride (hBN), we grow isotopically purified h10B15N crystals. Compared to [Formula: see text] in hBN with the natural distribution of isotopes, we observe substantially narrower and less crowded [Formula: see text] spin transitions as well as extended coherence time T2 and relaxation time T1. For quantum sensing, [Formula: see text] centers in our h10B15N samples exhibit a factor of 4 (2) enhancement in DC (AC) magnetic field sensitivity. For additional quantum resources, the individual addressability of the [Formula: see text] hyperfine levels enables the dynamical polarization and coherent control of the three nearest-neighbor 15N nuclear spins. Our results demonstrate the power of isotope engineering for enhancing the properties of quantum spin defects in hBN, and can be readily extended to improving spin qubits in a broad family of van der Waals materials.
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Affiliation(s)
- Ruotian Gong
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
| | - Xinyi Du
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
| | - Eli Janzen
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS, 66506, USA
| | - Vincent Liu
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Zhongyuan Liu
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
| | - Guanghui He
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
| | - Bingtian Ye
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Tongcang Li
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Norman Y Yao
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - James H Edgar
- Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, KS, 66506, USA
| | - Erik A Henriksen
- Department of Physics, Washington University, St. Louis, MO, 63130, USA
- Institute of Materials Science and Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Chong Zu
- Department of Physics, Washington University, St. Louis, MO, 63130, USA.
- Institute of Materials Science and Engineering, Washington University, St. Louis, MO, 63130, USA.
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21
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Borsoi F, Hendrickx NW, John V, Meyer M, Motz S, van Riggelen F, Sammak A, de Snoo SL, Scappucci G, Veldhorst M. Shared control of a 16 semiconductor quantum dot crossbar array. Nat Nanotechnol 2024; 19:21-27. [PMID: 37640909 PMCID: PMC10796274 DOI: 10.1038/s41565-023-01491-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 07/20/2023] [Indexed: 08/31/2023]
Abstract
The efficient control of a large number of qubits is one of the most challenging aspects for practical quantum computing. Current approaches in solid-state quantum technology are based on brute-force methods, where each and every qubit requires at least one unique control line-an approach that will become unsustainable when scaling to the required millions of qubits. Here, inspired by random-access architectures in classical electronics, we introduce the shared control of semiconductor quantum dots to efficiently operate a two-dimensional crossbar array in planar germanium. We tune the entire array, comprising 16 quantum dots, to the few-hole regime. We then confine an odd number of holes in each site to isolate an unpaired spin per dot. Moving forward, we demonstrate on a vertical and a horizontal double quantum dot a method for the selective control of the interdot coupling and achieve a tunnel coupling tunability over more than 10 GHz. The operation of a quantum electronic device with fewer control terminals than tunable experimental parameters represents a compelling step forward in the construction of scalable quantum technology.
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Affiliation(s)
- Francesco Borsoi
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
| | - Nico W Hendrickx
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Valentin John
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Marcel Meyer
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Sayr Motz
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Floor van Riggelen
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Amir Sammak
- QuTech and Netherlands Organisation for Applied Scientific Research (TNO), Delft, The Netherlands
| | - Sander L de Snoo
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Giordano Scappucci
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Menno Veldhorst
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
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22
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Gupta RS, Sundaresan N, Alexander T, Wood CJ, Merkel ST, Healy MB, Hillenbrand M, Jochym-O'Connor T, Wootton JR, Yoder TJ, Cross AW, Takita M, Brown BJ. Encoding a magic state with beyond break-even fidelity. Nature 2024; 625:259-263. [PMID: 38200302 PMCID: PMC10781628 DOI: 10.1038/s41586-023-06846-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/07/2023] [Indexed: 01/12/2024]
Abstract
To run large-scale algorithms on a quantum computer, error-correcting codes must be able to perform a fundamental set of operations, called logic gates, while isolating the encoded information from noise1-8. We can complete a universal set of logic gates by producing special resources called magic states9-11. It is therefore important to produce high-fidelity magic states to conduct algorithms while introducing a minimal amount of noise to the computation. Here we propose and implement a scheme to prepare a magic state on a superconducting qubit array using error correction. We find that our scheme produces better magic states than those that can be prepared using the individual qubits of the device. This demonstrates a fundamental principle of fault-tolerant quantum computing12, namely, that we can use error correction to improve the quality of logic gates with noisy qubits. Moreover, we show that the yield of magic states can be increased using adaptive circuits, in which the circuit elements are changed depending on the outcome of mid-circuit measurements. This demonstrates an essential capability needed for many error-correction subroutines. We believe that our prototype will be invaluable in the future as it can reduce the number of physical qubits needed to produce high-fidelity magic states in large-scale quantum-computing architectures.
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Affiliation(s)
- Riddhi S Gupta
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
- IBM Quantum, Almaden Research Center, San Jose, CA, USA
| | | | - Thomas Alexander
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | | | - Seth T Merkel
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Michael B Healy
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | | | - Tomas Jochym-O'Connor
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
- IBM Quantum, Almaden Research Center, San Jose, CA, USA
| | | | - Theodore J Yoder
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Andrew W Cross
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Maika Takita
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Benjamin J Brown
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA.
- IBM Denmark, Brøndby, Denmark.
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23
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Hecker K, Banszerus L, Schäpers A, Möller S, Peters A, Icking E, Watanabe K, Taniguchi T, Volk C, Stampfer C. Coherent charge oscillations in a bilayer graphene double quantum dot. Nat Commun 2023; 14:7911. [PMID: 38036517 PMCID: PMC10689829 DOI: 10.1038/s41467-023-43541-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023] Open
Abstract
The coherent dynamics of a quantum mechanical two-level system passing through an anti-crossing of two energy levels can give rise to Landau-Zener-Stückelberg-Majorana (LZSM) interference. LZSM interference spectroscopy has proven to be a fruitful tool to investigate charge noise and charge decoherence in semiconductor quantum dots (QDs). Recently, bilayer graphene has developed as a promising platform to host highly tunable QDs potentially useful for hosting spin and valley qubits. So far, in this system no coherent oscillations have been observed and little is known about charge noise in this material. Here, we report coherent charge oscillations and [Formula: see text] charge decoherence times in a bilayer graphene double QD. The charge decoherence times are measured independently using LZSM interference and photon assisted tunneling. Both techniques yield [Formula: see text] average values in the range of 400-500 ps. The observation of charge coherence allows to study the origin and spectral distribution of charge noise in future experiments.
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Affiliation(s)
- K Hecker
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany.
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Schäpers
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Peters
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
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24
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Rudolph T, Virmani SS. The two-qubit singlet/triplet measurement is universal for quantum computing given only maximally-mixed initial states. Nat Commun 2023; 14:7800. [PMID: 38016955 PMCID: PMC10684540 DOI: 10.1038/s41467-023-43481-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 11/10/2023] [Indexed: 11/30/2023] Open
Abstract
In order to delineate which minimalistic physical primitives can enable the full power of universal quantum computing, it has been fruitful to consider various measurement based architectures which reduce or eliminate the use of coherent unitary evolution, and also involve operations that are physically natural. In this context previous works had shown that the triplet-singlet measurement of two qubit angular momentum (or equivalently two qubit exchange symmetry) yields the power of quantum computation given access to a few additional different single qubit states or gates. However, Freedman, Hastings and Shokrian-Zini1 recently proposed a remarkable conjecture, called the 'STP=BQP' conjecture, which states that the two-qubit singlet/triplet measurement is quantum computationally universal given only an initial ensemble of maximally mixed single qubits. In this work we prove this conjecture. This provides a method for quantum computing that is fully rotationally symmetric (i.e. reference frame independent), using primitives that are physically very-accessible, naturally resilient to certain forms of error, and provably the simplest possible.
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Affiliation(s)
- Terry Rudolph
- Department of Physics, Imperial College London, London, SW7 2AZ, UK.
| | - Shashank Soyuz Virmani
- Department of Mathematics, Brunel University London, Kingston Ln, London, Uxbridge, UB8 3PH, UK.
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25
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Reuer K, Landgraf J, Fösel T, O'Sullivan J, Beltrán L, Akin A, Norris GJ, Remm A, Kerschbaum M, Besse JC, Marquardt F, Wallraff A, Eichler C. Realizing a deep reinforcement learning agent for real-time quantum feedback. Nat Commun 2023; 14:7138. [PMID: 37932251 PMCID: PMC10628214 DOI: 10.1038/s41467-023-42901-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 10/25/2023] [Indexed: 11/08/2023] Open
Abstract
Realizing the full potential of quantum technologies requires precise real-time control on time scales much shorter than the coherence time. Model-free reinforcement learning promises to discover efficient feedback strategies from scratch without relying on a description of the quantum system. However, developing and training a reinforcement learning agent able to operate in real-time using feedback has been an open challenge. Here, we have implemented such an agent for a single qubit as a sub-microsecond-latency neural network on a field-programmable gate array (FPGA). We demonstrate its use to efficiently initialize a superconducting qubit and train the agent based solely on measurements. Our work is a first step towards adoption of reinforcement learning for the control of quantum devices and more generally any physical device requiring low-latency feedback.
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Affiliation(s)
- Kevin Reuer
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland.
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland.
| | - Jonas Landgraf
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Thomas Fösel
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - James O'Sullivan
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Liberto Beltrán
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Abdulkadir Akin
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Graham J Norris
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Ants Remm
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Michael Kerschbaum
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Jean-Claude Besse
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Florian Marquardt
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Andreas Wallraff
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Christopher Eichler
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland.
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany.
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26
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Skoric L, Browne DE, Barnes KM, Gillespie NI, Campbell ET. Parallel window decoding enables scalable fault tolerant quantum computation. Nat Commun 2023; 14:7040. [PMID: 37923766 PMCID: PMC10624853 DOI: 10.1038/s41467-023-42482-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/12/2023] [Indexed: 11/06/2023] Open
Abstract
Large-scale quantum computers have the potential to hold computational capabilities beyond conventional computers. However, the physical qubits are prone to noise which must be corrected in order to perform fault-tolerant quantum computations. Quantum Error Correction (QEC) provides the path for realizing such computations. QEC generates a continuous stream of data that decoders must process at the rate it is received, which can be as fast as 1 μs per QEC round in superconducting quantum computers. If the decoder infrastructure cannot keep up, a data backlog problem is encountered and the computation runs exponentially slower. Today's leading approaches to quantum error correction are not scalable as existing decoders typically run slower as the problem size is increased, inevitably hitting the backlog problem. Here, we show how to parallelize decoding to achieve almost arbitrary speed, removing this roadblock to scalability. Our parallelization requires some classical feed forward decisions to be delayed, slowing-down the logical clock speed. However, the slow-down is now only polynomial in the size of the QEC code, averting the exponential slowdown. We numerically demonstrate our parallel decoder for the surface code, showing no noticeable reduction in logical fidelity compared to previous decoders and demonstrating the predicted speedup.
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Affiliation(s)
| | - Dan E Browne
- Riverlane, Cambridge, United Kingdom
- Dept. of Physics and Astronomy, University College London, London, WC1E 6BT, UK
| | | | | | - Earl T Campbell
- Riverlane, Cambridge, United Kingdom.
- Dept. of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK.
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27
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Leib D, Seidel T, Jäger S, Heese R, Jones C, Awasthi A, Niederle A, Bortz M. An optimization case study for solving a transport robot scheduling problem on quantum-hybrid and quantum-inspired hardware. Sci Rep 2023; 13:18743. [PMID: 37907614 PMCID: PMC10618446 DOI: 10.1038/s41598-023-45668-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 10/22/2023] [Indexed: 11/02/2023] Open
Abstract
We present a comprehensive case study comparing the performance of D-Waves' quantum-classical hybrid framework, Fujitsu's quantum-inspired digital annealer, and Gurobi's state-of-the-art classical solver in solving a transport robot scheduling problem. This problem originates from an industrially relevant real-world scenario. We provide three different models for our problem following different design philosophies. In our benchmark, we focus on the solution quality and end-to-end runtime of different model and solver combinations. We find promising results for the digital annealer and some opportunities for the hybrid quantum annealer in direct comparison with Gurobi. Our study provides insights into the workflow for solving an application-oriented optimization problem with different strategies, and can be useful for evaluating the strengths and weaknesses of different approaches.
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Affiliation(s)
- Dominik Leib
- Fraunhofer ITWM, Optimization Department, 67663, Kaiserslautern, Germany.
| | - Tobias Seidel
- Fraunhofer ITWM, Optimization Department, 67663, Kaiserslautern, Germany
| | - Sven Jäger
- Fraunhofer ITWM, Optimization Department, 67663, Kaiserslautern, Germany
| | - Raoul Heese
- Fraunhofer ITWM, Optimization Department, 67663, Kaiserslautern, Germany
| | - Caitlin Jones
- BASF Digital Solutions GmbH, 67061, Ludwigshafen am Rhein, Germany
| | - Abhishek Awasthi
- BASF Digital Solutions GmbH, 67061, Ludwigshafen am Rhein, Germany
| | | | - Michael Bortz
- Fraunhofer ITWM, Optimization Department, 67663, Kaiserslautern, Germany
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28
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Silva TL, Taddei MM, Carrazza S, Aolita L. Fragmented imaginary-time evolution for early-stage quantum signal processors. Sci Rep 2023; 13:18258. [PMID: 37880355 PMCID: PMC10600201 DOI: 10.1038/s41598-023-45540-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 10/20/2023] [Indexed: 10/27/2023] Open
Abstract
Simulating quantum imaginary-time evolution (QITE) is a significant promise of quantum computation. However, the known algorithms are either probabilistic (repeat until success) with unpractically small success probabilities or coherent (quantum amplitude amplification) with circuit depths and ancillary-qubit numbers unrealistically large in the mid-term. Our main contribution is a new generation of deterministic, high-precision QITE algorithms that are significantly more amenable experimentally. A surprisingly simple idea is behind them: partitioning the evolution into a sequence of fragments that are run probabilistically. It causes a considerable reduction in wasted circuit depth every time a run fails. Remarkably, the resulting overall runtime is asymptotically better than in coherent approaches, and the hardware requirements are even milder than in probabilistic ones. Our findings are especially relevant for the early fault-tolerance stages of quantum hardware.
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Affiliation(s)
- Thais L Silva
- Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, UAE.
- Federal University of Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ, 21941-972, Brazil.
| | - Márcio M Taddei
- Federal University of Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ, 21941-972, Brazil
- ICFO - Institut de Ciencies Fotòniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels, Barcelona, Spain
| | - Stefano Carrazza
- Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, UAE
- TIF Lab, Dipartimento di Fisica, Università degli Studi di Milano and INFN Sezione di Milano, Milan, Italy
| | - Leandro Aolita
- Quantum Research Centre, Technology Innovation Institute, Abu Dhabi, UAE
- Federal University of Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ, 21941-972, Brazil
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29
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Le TK, Nguyen HQ, Ho LB. Variational quantum metrology for multiparameter estimation under dephasing noise. Sci Rep 2023; 13:17775. [PMID: 37853037 PMCID: PMC10584960 DOI: 10.1038/s41598-023-44786-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/12/2023] [Indexed: 10/20/2023] Open
Abstract
We present a hybrid quantum-classical variational scheme to enhance precision in quantum metrology. In the scheme, both the initial state and the measurement basis in the quantum part are parameterized and optimized via the classical part. It enables the maximization of information gained about the measured quantity. We discuss specific applications to 3D magnetic field sensing under several dephasing noise models. Indeed, we demonstrate its ability to simultaneously estimate all parameters and surpass the standard quantum limit, making it a powerful tool for metrological applications.
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Affiliation(s)
- Trung Kien Le
- Department of Physics, University of California, Santa Barbara, Santa Barbara, USA
- Department of Applied Physics, Stanford University, Stanford, California, 94305, USA
| | - Hung Q Nguyen
- Nano and Energy Center, University of Science, Vietnam National University, Hanoi, 120401, Vietnam
| | - Le Bin Ho
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, 980-8578, Japan.
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan.
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30
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He XL, Lu Y, Bao DQ, Xue H, Jiang WB, Wang Z, Roudsari AF, Delsing P, Tsai JS, Lin ZR. Fast generation of Schrödinger cat states using a Kerr-tunable superconducting resonator. Nat Commun 2023; 14:6358. [PMID: 37821443 PMCID: PMC10567735 DOI: 10.1038/s41467-023-42057-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/28/2023] [Indexed: 10/13/2023] Open
Abstract
Schrödinger cat states, quantum superpositions of macroscopically distinct classical states, are an important resource for quantum communication, quantum metrology and quantum computation. Especially, cat states in a phase space protected against phase-flip errors can be used as a logical qubit. However, cat states, normally generated in three-dimensional cavities and/or strong multi-photon drives, are facing the challenges of scalability and controllability. Here, we present a strategy to generate and preserve cat states in a coplanar superconducting circuit by the fast modulation of Kerr nonlinearity. At the Kerr-free work point, our cat states are passively preserved due to the vanishing Kerr effect. We are able to prepare a 2-component cat state in our chip-based device with a fidelity reaching 89.1% under a 96 ns gate time. Our scheme shows an excellent route to constructing a chip-based bosonic quantum processor.
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Affiliation(s)
- X L He
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Yong Lu
- 3rd Physikalisches Institut, University of Stuttgart, 70569, Stuttgart, Germany.
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
| | - D Q Bao
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Hang Xue
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - W B Jiang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - Z Wang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China
- University of Chinese Academy of Science, 100049, Beijing, China
| | - A F Roudsari
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - Per Delsing
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
| | - J S Tsai
- Graduate School of Science, Tokyo University of Science, Shinjuku, Tokyo, 162-0825, Japan
- Center for Quantum Computing, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Z R Lin
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China.
- University of Chinese Academy of Science, 100049, Beijing, China.
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31
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Lledó C, Dassonneville R, Moulinas A, Cohen J, Shillito R, Bienfait A, Huard B, Blais A. Cloaking a qubit in a cavity. Nat Commun 2023; 14:6313. [PMID: 37813905 PMCID: PMC10562410 DOI: 10.1038/s41467-023-42060-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 09/28/2023] [Indexed: 10/11/2023] Open
Abstract
Cavity quantum electrodynamics (QED) uses a cavity to engineer the mode structure of the vacuum electromagnetic field such as to enhance the interaction between light and matter. Exploiting these ideas in solid-state systems has lead to circuit QED which has emerged as a valuable tool to explore the rich physics of quantum optics and as a platform for quantum computation. Here we introduce a simple approach to further engineer the light-matter interaction in a driven cavity by controllably decoupling a qubit from the cavity's photon population, effectively cloaking the qubit from the cavity. This is realized by driving the qubit with an external tone tailored to destructively interfere with the cavity field, leaving the qubit to interact with a cavity which appears to be in the vacuum state. Our experiment demonstrates how qubit cloaking can be exploited to cancel the ac-Stark shift and measurement-induced dephasing, and to accelerate qubit readout. In addition to qubit readout, applications of this method include qubit logical operations and the preparation of non-classical cavity states in circuit QED and other cavity-based setups.
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Affiliation(s)
- Cristóbal Lledó
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1 QC, Canada.
| | - Rémy Dassonneville
- Ecole Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, F-69342, Lyon, France
| | - Adrien Moulinas
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1 QC, Canada
| | - Joachim Cohen
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1 QC, Canada
| | - Ross Shillito
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1 QC, Canada
| | - Audrey Bienfait
- Ecole Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, F-69342, Lyon, France
| | - Benjamin Huard
- Ecole Normale Supérieure de Lyon, CNRS, Laboratoire de Physique, F-69342, Lyon, France
| | - Alexandre Blais
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1 QC, Canada
- Canadian Institute for Advanced Research, Toronto, ON, M5G1M1, Canada
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32
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Rahman AU, Ali H, Zangi SM, Qiao CF. Extremal quantum correlation generation using a hybrid channel. Sci Rep 2023; 13:16654. [PMID: 37789025 PMCID: PMC10547701 DOI: 10.1038/s41598-023-43811-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/28/2023] [Indexed: 10/05/2023] Open
Abstract
The preservation of quantum correlations requires optimal procedures and the proper design of the transmitting channels. In this regard, we address designing a hybrid channel comprising a single-mode cavity accompanied by a super-Gaussian beam and local dephasing parts based on the dynamics of quantum characteristics. We choose two-level atoms and various functions such as traced-distance discord, concurrence, and local-quantum uncertainty to analyze the effectiveness of the hybrid channel to preserve quantum correlations along with entropy suppression discussed using linear entropy. The joint configuration of the considered fields is found to not only preserve but also generate quantum correlations even in the presence of local dephasing. Most importantly, within certain limits, the proposed channel can be readily regulated to generate maximal quantum correlations and complete suppression of the disorder. Besides, compared to the individual parts, mixing the Fock state cavity, super-Gaussian beam, and local dephasing remains a resourceful choice for the prolonged quantum correlations' preservation. Finally, we present an interrelationship between the considered two-qubit correlations' functions, showing the deviation between each two correlations and of the considered state from maximal entanglement under the influence of the assumed hybrid channel.
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Affiliation(s)
- Atta Ur Rahman
- School of Physics, University of Chinese Academy of Science, Yuquan Road 19A, Beijing, 100049, China
| | - Hazrat Ali
- Abbottabad University of Science and Technology, Havellian, KP, 22500, Pakistan
| | - S M Zangi
- School of Physics and Astronomy, Yunnan University, Kunming, 650500, China
| | - Cong-Feng Qiao
- School of Physics, University of Chinese Academy of Science, Yuquan Road 19A, Beijing, 100049, China.
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33
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Evered SJ, Bluvstein D, Kalinowski M, Ebadi S, Manovitz T, Zhou H, Li SH, Geim AA, Wang TT, Maskara N, Levine H, Semeghini G, Greiner M, Vuletić V, Lukin MD. High-fidelity parallel entangling gates on a neutral-atom quantum computer. Nature 2023; 622:268-272. [PMID: 37821591 PMCID: PMC10567572 DOI: 10.1038/s41586-023-06481-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 07/25/2023] [Indexed: 10/13/2023]
Abstract
The ability to perform entangling quantum operations with low error rates in a scalable fashion is a central element of useful quantum information processing1. Neutral-atom arrays have recently emerged as a promising quantum computing platform, featuring coherent control over hundreds of qubits2,3 and any-to-any gate connectivity in a flexible, dynamically reconfigurable architecture4. The main outstanding challenge has been to reduce errors in entangling operations mediated through Rydberg interactions5. Here we report the realization of two-qubit entangling gates with 99.5% fidelity on up to 60 atoms in parallel, surpassing the surface-code threshold for error correction6,7. Our method uses fast, single-pulse gates based on optimal control8, atomic dark states to reduce scattering9 and improvements to Rydberg excitation and atom cooling. We benchmark fidelity using several methods based on repeated gate applications10,11, characterize the physical error sources and outline future improvements. Finally, we generalize our method to design entangling gates involving a higher number of qubits, which we demonstrate by realizing low-error three-qubit gates12,13. By enabling high-fidelity operation in a scalable, highly connected system, these advances lay the groundwork for large-scale implementation of quantum algorithms14, error-corrected circuits7 and digital simulations15.
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Affiliation(s)
- Simon J Evered
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Dolev Bluvstein
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Sepehr Ebadi
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Tom Manovitz
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Hengyun Zhou
- Department of Physics, Harvard University, Cambridge, MA, USA
- QuEra Computing Inc., Boston, MA, USA
| | - Sophie H Li
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Tout T Wang
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Nishad Maskara
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Harry Levine
- Department of Physics, Harvard University, Cambridge, MA, USA
- AWS Center for Quantum Computing, Pasadena, CA, USA
| | - Giulia Semeghini
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Markus Greiner
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Vladan Vuletić
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mikhail D Lukin
- Department of Physics, Harvard University, Cambridge, MA, USA.
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34
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Hoke JC, Ippoliti M, Rosenberg E, Abanin D, Acharya R, Andersen TI, Ansmann M, Arute F, Arya K, Asfaw A, Atalaya J, Bardin JC, Bengtsson A, Bortoli G, Bourassa A, Bovaird J, Brill L, Broughton M, Buckley BB, Buell DA, Burger T, Burkett B, Bushnell N, Chen Z, Chiaro B, Chik D, Cogan J, Collins R, Conner P, Courtney W, Crook AL, Curtin B, Dau AG, Debroy DM, Del Toro Barba A, Demura S, Di Paolo A, Drozdov IK, Dunsworth A, Eppens D, Erickson C, Farhi E, Fatemi R, Ferreira VS, Burgos LF, Forati E, Fowler AG, Foxen B, Giang W, Gidney C, Gilboa D, Giustina M, Gosula R, Gross JA, Habegger S, Hamilton MC, Hansen M, Harrigan MP, Harrington SD, Heu P, Hoffmann MR, Hong S, Huang T, Huff A, Huggins WJ, Isakov SV, Iveland J, Jeffrey E, Jiang Z, Jones C, Juhas P, Kafri D, Kechedzhi K, Khattar T, Khezri M, Kieferová M, Kim S, Kitaev A, Klimov PV, Klots AR, Korotkov AN, Kostritsa F, Kreikebaum JM, Landhuis D, Laptev P, Lau KM, Laws L, Lee J, Lee KW, Lensky YD, Lester BJ, Lill AT, Liu W, Locharla A, Martin O, McClean JR, McEwen M, Miao KC, Mieszala A, Montazeri S, Morvan A, Movassagh R, Mruczkiewicz W, Neeley M, Neill C, Nersisyan A, Newman M, Ng JH, Nguyen A, Nguyen M, Niu MY, O’Brien TE, Omonije S, Opremcak A, Petukhov A, Potter R, Pryadko LP, Quintana C, Rocque C, Rubin NC, Saei N, Sank D, Sankaragomathi K, Satzinger KJ, Schurkus HF, Schuster C, Shearn MJ, Shorter A, Shutty N, Shvarts V, Skruzny J, Smith WC, Somma R, Sterling G, Strain D, Szalay M, Torres A, Vidal G, Villalonga B, Heidweiller CV, White T, Woo BWK, Xing C, Yao ZJ, Yeh P, Yoo J, Young G, Zalcman A, Zhang Y, Zhu N, Zobrist N, Neven H, Babbush R, Bacon D, Boixo S, Hilton J, Lucero E, Megrant A, Kelly J, Chen Y, Smelyanskiy V, Mi X, Khemani V, Roushan P. Measurement-induced entanglement and teleportation on a noisy quantum processor. Nature 2023; 622:481-486. [PMID: 37853150 PMCID: PMC10584681 DOI: 10.1038/s41586-023-06505-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 08/01/2023] [Indexed: 10/20/2023]
Abstract
Measurement has a special role in quantum theory1: by collapsing the wavefunction, it can enable phenomena such as teleportation2 and thereby alter the 'arrow of time' that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time3-10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium11-13. For present-day noisy intermediate-scale quantum (NISQ) processors14, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping9,15-17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling3,4 to measurement-induced teleportation18. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors.
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35
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Lu Y, Maiti A, Garmon JWO, Ganjam S, Zhang Y, Claes J, Frunzio L, Girvin SM, Schoelkopf RJ. Author Correction: High-fidelity parametric beamsplitting with a parity-protected converter. Nat Commun 2023; 14:6055. [PMID: 37770438 PMCID: PMC10539307 DOI: 10.1038/s41467-023-41822-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023] Open
Affiliation(s)
- Yao Lu
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
| | - Aniket Maiti
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
| | - John W O Garmon
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Suhas Ganjam
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Yaxing Zhang
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Jahan Claes
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Luigi Frunzio
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Steven M Girvin
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Robert J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
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36
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Wang S, Baksi A, Chattopadhyay A. A Higher radix architecture for quantum carry-lookahead adder. Sci Rep 2023; 13:16338. [PMID: 37770461 PMCID: PMC10539406 DOI: 10.1038/s41598-023-41122-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 08/22/2023] [Indexed: 09/30/2023] Open
Abstract
In this paper, we propose an efficient quantum carry-lookahead adder based on the higher radix structure. For the addition of two n-bit numbers, our adder uses [Formula: see text] qubits and [Formula: see text] T gates to get the correct answer in T-depth [Formula: see text], where r is the radix. Quantum carry-lookahead adder has already attracted some attention because of its low T-depth. Our work further reduces the overall cost by introducing a higher radix layer. By analyzing the performance in T-depth, T-count, and qubit count, it is shown that the proposed adder is superior to existing quantum carry-lookahead adders. Even compared to the Draper out-of-place adder which is very compact and efficient, our adder is still better in terms of T-count.
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Affiliation(s)
- Siyi Wang
- School of Computer Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
| | - Anubhab Baksi
- School of Computer Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Anupam Chattopadhyay
- School of Computer Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
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37
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Mackeprang J, Bhatti D, Barz S. Non-adaptive measurement-based quantum computation on IBM Q. Sci Rep 2023; 13:15428. [PMID: 37723342 PMCID: PMC10507095 DOI: 10.1038/s41598-023-41025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 08/21/2023] [Indexed: 09/20/2023] Open
Abstract
We test the quantumness of IBM's quantum computer IBM Quantum System One in Ehningen, Germany. We generate generalised n-qubit GHZ states and measure Bell inequalities to investigate the n-party entanglement of the GHZ states. The implemented Bell inequalities are derived from non-adaptive measurement-based quantum computation (NMQC), a type of quantum computing that links the successful computation of a non-linear function to the violation of a multipartite Bell-inequality. The goal is to compute a multivariate Boolean function that clearly differentiates non-local correlations from local hidden variables (LHVs). Since it has been shown that LHVs can only compute linear functions, whereas quantum correlations are capable of outputting every possible Boolean function it thus serves as an indicator of multipartite entanglement. Here, we compute various non-linear functions with NMQC on IBM's quantum computer IBM Quantum System One and thereby demonstrate that the presented method can be used to characterize quantum devices. We find a violation for a maximum of seven qubits and compare our results to an existing implementation of NMQC using photons.
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Affiliation(s)
- Jelena Mackeprang
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569, Stuttgart, Germany
- Center for Integrated Quantum Science and Technology (IQST), University of Stuttgart, 70569, Stuttgart, Germany
- QuSoft and Centrum Wiskunde & Informatica (CWI), Science Park 123, 1098 XG, Amsterdam, The Netherlands
| | - Daniel Bhatti
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569, Stuttgart, Germany
- Center for Integrated Quantum Science and Technology (IQST), University of Stuttgart, 70569, Stuttgart, Germany
| | - Stefanie Barz
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569, Stuttgart, Germany.
- Center for Integrated Quantum Science and Technology (IQST), University of Stuttgart, 70569, Stuttgart, Germany.
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38
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Lu Y, Maiti A, Garmon JWO, Ganjam S, Zhang Y, Claes J, Frunzio L, Girvin SM, Schoelkopf RJ. High-fidelity parametric beamsplitting with a parity-protected converter. Nat Commun 2023; 14:5767. [PMID: 37723141 PMCID: PMC10507116 DOI: 10.1038/s41467-023-41104-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 08/23/2023] [Indexed: 09/20/2023] Open
Abstract
Fast, high-fidelity operations between microwave resonators are an important tool for bosonic quantum computation and simulation with superconducting circuits. An attractive approach for implementing these operations is to couple these resonators via a nonlinear converter and actuate parametric processes with RF drives. It can be challenging to make these processes simultaneously fast and high fidelity, since this requires introducing strong drives without activating parasitic processes or introducing additional decoherence channels. We show that in addition to a careful management of drive frequencies and the spectrum of environmental noise, leveraging the inbuilt symmetries of the converter Hamiltonian can suppress unwanted nonlinear interactions, preventing converter-induced decoherence. We demonstrate these principles using a differentially-driven DC-SQUID as our converter, coupled to two high-Q microwave cavities. Using this architecture, we engineer a highly-coherent beamsplitter and fast (~100 ns) swaps between the cavities, limited primarily by their intrinsic single-photon loss. We characterize this beamsplitter in the cavities' joint single-photon subspace, and show that we can detect and post-select photon loss events to achieve a beamsplitter gate fidelity exceeding 99.98%, which to our knowledge far surpasses the current state of the art.
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Affiliation(s)
- Yao Lu
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
| | - Aniket Maiti
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
| | - John W O Garmon
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Suhas Ganjam
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Yaxing Zhang
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Jahan Claes
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Luigi Frunzio
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Steven M Girvin
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA
| | - Robert J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, 06511, CT, USA.
- Yale Quantum Institute, Yale University, New Haven, 06511, CT, USA.
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39
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Timoshuk I, Tikhonov K, Makhlin Y. Quantum computation at the edge of a disordered Kitaev honeycomb lattice. Sci Rep 2023; 13:15263. [PMID: 37709834 PMCID: PMC10502100 DOI: 10.1038/s41598-023-41997-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 09/04/2023] [Indexed: 09/16/2023] Open
Abstract
We analyze propagation of quantum information along chiral Majorana edge states in two-dimensional topological materials. The use of edge states may facilitate the braiding operation, an important ingredient in topological quantum computations. For the edge of the Kitaev honeycomb model in a topological phase, we discuss how the edge states can participate in quantum-information processing, and consider a two-qubit logic gate between distant external qubits coupled to the edge. Here we analyze the influence of disorder and noise on properties of the edge states and quantum-gate fidelity. We find that realistically weak disorder does not prevent one from implementation of a high-fidelity operation via the edge.
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Affiliation(s)
- Igor Timoshuk
- Condensed-Matter Physics Laboratory, HSE University, 101000, Moscow, Russia
| | - Konstantin Tikhonov
- L. D. Landau Institute for Theoretical Physics, 142432, Chernogolovka, Russia
| | - Yuriy Makhlin
- Condensed-Matter Physics Laboratory, HSE University, 101000, Moscow, Russia.
- L. D. Landau Institute for Theoretical Physics, 142432, Chernogolovka, Russia.
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40
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Varley JB, Ray KG, Lordi V. Dangling Bonds as Possible Contributors to Charge Noise in Silicon and Silicon-Germanium Quantum Dot Qubits. ACS Appl Mater Interfaces 2023; 15:43111-43123. [PMID: 37651689 DOI: 10.1021/acsami.3c06725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Spin qubits based on Si and Si1-xGex quantum dot architectures exhibit among the best coherence times of competing quantum computing technologies, yet they still suffer from charge noise that limit their qubit gate fidelities. Identifying the origins of these charge fluctuations is therefore a critical step toward improving Si quantum-dot-based qubits. Here, we use hybrid functional calculations to investigate possible atomistic sources of charge noise, focusing on charge trapping at Si and Ge dangling bonds (DBs). We evaluate the role of global and local environment in the defect levels associated with DBs in Si, Ge, and Si1-xGex alloys, and consider their trapping and excitation energies within the framework of configuration coordinate diagrams. We additionally consider the influence of strain and oxidation in charge-trapping energetics by analyzing Si and GeSi DBs in SiO2 and strained Si layers in typical Si1-xGex quantum dot heterostructures. Our results identify that Ge dangling bonds are more problematic charge-trapping centers both in typical Si1-xGex alloys and associated oxidation layers, and they may be exacerbated by compositional inhomogeneities. These results suggest the importance of alloy homogeneity and possible passivation schemes for DBs in Si-based quantum dot qubits and are of general relevance to mitigating possible trap levels in other Si, Ge, and Si1-xGex-based metal-oxide-semiconductor stacks and related devices.
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Affiliation(s)
- Joel B Varley
- Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Keith G Ray
- Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Vincenzo Lordi
- Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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41
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Zahia AA, Abd-Rabbou MY, Megahed AM, Obada ASF. Bidirectional field-steering and atomic steering induced by a magnon mode in a qubit-photon system. Sci Rep 2023; 13:14943. [PMID: 37696940 PMCID: PMC10495356 DOI: 10.1038/s41598-023-41907-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 09/01/2023] [Indexed: 09/13/2023] Open
Abstract
This paper investigates the cavity-magnon steering and qubit-qubit steering of a hybrid quantum system consisting of a single-mode magnon, a two-qubit state, and a single-mode cavity field in the presence of their damping rates. The temporal wave vector of the system is obtained for the initial maximally entangled two-qubit state and initial vacuum state of the magnon and cavity modes. Additionally, the mathematical inequalities for obtaining the cavity-magnon steering and qubit-qubit steering are introduced. The findings reveal that steering between the magnon and cavity is asymmetric, while steering between the two qubits is symmetric in our system. Increasing the atom-field coupling improves steering from magnon to field, while reducing steering between the two qubits. Moreover, increasing magnon-field coupling enhances and elevates the lower bounds of qubit-qubit steering. Further, adding the damping rates causes deterioration of the cavity-magnon steering and qubit-qubit steering. However, the steering persistence is slightly greater when damping originates from the cavity field rather than the magnon modes based on the coupling parameters.
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Affiliation(s)
- Ahmed A Zahia
- Department of Mathematics, Faculty of Science, Benha University, Benha, Egypt
| | - M Y Abd-Rabbou
- Mathematics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, 11884, Egypt.
| | - Ahmed M Megahed
- Department of Mathematics, Faculty of Science, Benha University, Benha, Egypt
| | - A-S F Obada
- Mathematics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, 11884, Egypt
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42
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Li X. Optimal control of quantum state preparation and entanglement creation in two-qubit quantum system with bounded amplitude. Sci Rep 2023; 13:14734. [PMID: 37679384 PMCID: PMC10484962 DOI: 10.1038/s41598-023-41688-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023] Open
Abstract
We consider the optimal control problem in a two-qubit system with bounded amplitude. Two cases are studied: quantum state preparation and entanglement creation. Cost functions, fidelity and concurrence, are optimized over bang-off controls for various values of the total duration, respectively. For quantum state preparation problem, three critical time points are determined accurately, and optimal controls are estimated. A better estimation of the quantum speed limit is obtained, so is the time-optimal control. For entanglement creation problem, two critical time points are determined, one of them is the minimal time to achieve maximal entanglement (unit concurrence) starting from the product state. In addition, the comparisons between bang-off and chopped random basis (CRAB) are made.
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Affiliation(s)
- Xikun Li
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China.
- Max-Planck-Institut für Physik komplexer Systeme, 01187, Dresden, Germany.
- Department of Physics and Astronomy, Aarhus University, 8000, Aarhus, Denmark.
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43
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Xiang ZC, Huang K, Zhang YR, Liu T, Shi YH, Deng CL, Liu T, Li H, Liang GH, Mei ZY, Yu H, Xue G, Tian Y, Song X, Liu ZB, Xu K, Zheng D, Nori F, Fan H. Simulating Chern insulators on a superconducting quantum processor. Nat Commun 2023; 14:5433. [PMID: 37669968 PMCID: PMC10480218 DOI: 10.1038/s41467-023-41230-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 08/23/2023] [Indexed: 09/07/2023] Open
Abstract
The quantum Hall effect, fundamental in modern condensed matter physics, continuously inspires new theories and predicts emergent phases of matter. Here we experimentally demonstrate three types of Chern insulators with synthetic dimensions on a programable 30-qubit-ladder superconducting processor. We directly measure the band structures of the 2D Chern insulator along synthetic dimensions with various configurations of Aubry-André-Harper chains and observe dynamical localisation of edge excitations. With these two signatures of topology, our experiments implement the bulk-edge correspondence in the synthetic 2D Chern insulator. Moreover, we simulate two different bilayer Chern insulators on the ladder-type superconducting processor. With the same and opposite periodically modulated on-site potentials for two coupled chains, we simulate topologically nontrivial edge states with zero Hall conductivity and a Chern insulator with higher Chern numbers, respectively. Our work shows the potential of using superconducting qubits for investigating different intriguing topological phases of quantum matter.
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Affiliation(s)
- Zhong-Cheng Xiang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Kaixuan Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300457, China
| | - Yu-Ran Zhang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, 510640, China
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan
- Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Tao Liu
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, 510640, China
| | - Yun-Hao Shi
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Cheng-Lin Deng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Tong Liu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hao Li
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Gui-Han Liang
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zheng-Yang Mei
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Haifeng Yu
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Guangming Xue
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Ye Tian
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiaohui Song
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhi-Bo Liu
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300457, China
| | - Kai Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
| | - Dongning Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Center for Quantum Computing, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Physics Department, University of Michigan, Ann Arbor, MI, 48109-1040, USA.
| | - Heng Fan
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
- CAS Centre for Excellence in Topological Quantum Computation, UCAS, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
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44
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Geller MR. Proposal for a Lorenz qubit. Sci Rep 2023; 13:14106. [PMID: 37644072 PMCID: PMC10465570 DOI: 10.1038/s41598-023-40893-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 08/17/2023] [Indexed: 08/31/2023] Open
Abstract
Nonlinear qubit master equations have recently been shown to exhibit rich dynamical phenomena such as period doubling, Hopf bifurcation, and strange attractors usually associated with classical nonlinear systems. Here we investigate nonlinear qubit models that support tunable Lorenz attractors. A Lorenz qubit could be realized experimentally by combining qubit torsion, generated by real or simulated mean field dynamics, with linear amplification and dissipation. This would extend engineered Lorenz systems to the quantum regime, allowing for their direct experimental study and possible application to quantum information processing.
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Affiliation(s)
- Michael R Geller
- Center for Simulational Physics, University of Georgia, Athens, GA, 30602, USA.
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45
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Rizzato R, Schalk M, Mohr S, Hermann JC, Leibold JP, Bruckmaier F, Salvitti G, Qian C, Ji P, Astakhov GV, Kentsch U, Helm M, Stier AV, Finley JJ, Bucher DB. Extending the coherence of spin defects in hBN enables advanced qubit control and quantum sensing. Nat Commun 2023; 14:5089. [PMID: 37607945 PMCID: PMC10444786 DOI: 10.1038/s41467-023-40473-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/26/2023] [Indexed: 08/24/2023] Open
Abstract
Negatively-charged boron vacancy centers ([Formula: see text]) in hexagonal Boron Nitride (hBN) are attracting increasing interest since they represent optically-addressable qubits in a van der Waals material. In particular, these spin defects have shown promise as sensors for temperature, pressure, and static magnetic fields. However, their short spin coherence time limits their scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by two orders of magnitude, approaching the fundamental T1 relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect radiofrequency signals with sub-Hz resolution. The corresponding sensitivity is benchmarked against that of state-of-the-art NV-diamond quantum sensors. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures.
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Affiliation(s)
- Roberto Rizzato
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany.
- University of Bari, Department of Physics "M. Merlin", Via Amendola 173, Bari, 70125, Italy.
| | - Martin Schalk
- Walter Schottky Institute, TUM School of Natural Sciences, Am Coulombwall 4, Garching bei München, 85748, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, München, D-80799, Germany
| | - Stephan Mohr
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany
| | - Jens C Hermann
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, München, D-80799, Germany
| | - Joachim P Leibold
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany
- Technical University of Munich, TUM School of Natural Sciences, Department of Physics, James-Franck-Str. 1, Garching bei München, 85748, Germany
| | - Fleming Bruckmaier
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany
| | - Giovanna Salvitti
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany
- University of Bologna, Department of Chemistry "G. Ciamician", Via Selmi, 2, Bologna, 40126, Italy
| | - Chenjiang Qian
- Walter Schottky Institute, TUM School of Natural Sciences, Am Coulombwall 4, Garching bei München, 85748, Germany
| | - Peirui Ji
- Walter Schottky Institute, TUM School of Natural Sciences, Am Coulombwall 4, Garching bei München, 85748, Germany
| | - Georgy V Astakhov
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, Dresden, 01328, Germany
| | - Ulrich Kentsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, Dresden, 01328, Germany
| | - Manfred Helm
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, Dresden, 01328, Germany
- TU Dresden, 01062, Dresden, Germany
| | - Andreas V Stier
- Walter Schottky Institute, TUM School of Natural Sciences, Am Coulombwall 4, Garching bei München, 85748, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, München, D-80799, Germany
| | - Jonathan J Finley
- Walter Schottky Institute, TUM School of Natural Sciences, Am Coulombwall 4, Garching bei München, 85748, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, München, D-80799, Germany
| | - Dominik B Bucher
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstraße 4, Garching bei München, 85748, Germany.
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, München, D-80799, Germany.
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46
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Vićentijević M, Jakšić M, Suligoj T. Implantation site design for large area diamond quantum device fabrication. Sci Rep 2023; 13:13483. [PMID: 37596364 PMCID: PMC10439203 DOI: 10.1038/s41598-023-40785-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/16/2023] [Indexed: 08/20/2023] Open
Abstract
With the number of qubits increasing with each new quantum processor design, it is to be expected that the area of the future quantum devices will become larger. As diamond is one of the promising materials for solid state quantum devices fabricated by ion implantation, we developed a single board diamond detector/preamplifier implantation system to serve as a testbed for implantation sites of different areas and geometry. We determined that for simple circular openings in a detector electrode, the uniformity of detection of the impinging ions increases as the area of the sites decreases. By altering the implantation site design and introducing lateral electric field, we were able to increase the area of the implantation site by an order of magnitude, without decreasing the detection uniformity. Successful detection of 140 keV copper ions that penetrate on average under 100 nm was demonstrated, over the 800 µm2 area implantation site (large enough to accommodate over 2 × 105 possible qubits), with 100% detection efficiency. The readout electronics of the implantation system were calibrated by a referent 241Am gamma source, achieving an equivalent noise charge value of 48 electrons, at room temperature, less than 1% of the energy of impinging ions.
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Affiliation(s)
- Milan Vićentijević
- Ruđer Bošković Institute, 10000, Zagreb, Croatia.
- Department of Electronics, Microelectronics, Computer and Intelligent Systems, Faculty of Electrical Engineering and Computing, University of Zagreb, 10000, Zagreb, Croatia.
| | - Milko Jakšić
- Ruđer Bošković Institute, 10000, Zagreb, Croatia
| | - Tomislav Suligoj
- Department of Electronics, Microelectronics, Computer and Intelligent Systems, Faculty of Electrical Engineering and Computing, University of Zagreb, 10000, Zagreb, Croatia
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47
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Diviánszky P, Márton I, Bene E, Vértesi T. Certification of qubits in the prepare-and-measure scenario with large input alphabet and connections with the Grothendieck constant. Sci Rep 2023; 13:13200. [PMID: 37580385 PMCID: PMC10425422 DOI: 10.1038/s41598-023-39529-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 07/26/2023] [Indexed: 08/16/2023] Open
Abstract
We address the problem of testing the quantumness of two-dimensional systems in the prepare-and-measure (PM) scenario, using a large number of preparations and a large number of measurement settings, with binary outcome measurements. In this scenario, we introduce constants, which we relate to the Grothendieck constant of order 3. We associate them with the white noise resistance of the prepared qubits and to the critical detection efficiency of the measurements performed. Large-scale numerical tools are used to bound the constants. This allows us to obtain new bounds on the minimum detection efficiency that a setup with 70 preparations and 70 measurement settings can tolerate.
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Affiliation(s)
- Péter Diviánszky
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - István Márton
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - Erika Bene
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - Tamás Vértesi
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary.
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48
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Goss N, Morvan A, Marinelli B, Mitchell BK, Nguyen LB, Naik RK, Chen L, Jünger C, Kreikebaum JM, Santiago DI, Wallman JJ, Siddiqi I. Author Correction: High-fidelity qutrit entangling gates for superconducting circuits. Nat Commun 2023; 14:4256. [PMID: 37460551 PMCID: PMC10352233 DOI: 10.1038/s41467-023-40049-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023] Open
Affiliation(s)
- Noah Goss
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Alexis Morvan
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brian Marinelli
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Bradley K Mitchell
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Long B Nguyen
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ravi K Naik
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Larry Chen
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Christian Jünger
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - John Mark Kreikebaum
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - David I Santiago
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joel J Wallman
- Keysight Technologies Canada, Kanata, ON, K2K 2W5, Canada
| | - Irfan Siddiqi
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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49
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McLellan RA, Dutta A, Zhou C, Jia Y, Weiland C, Gui X, Place APM, Crowley KD, Le XH, Madhavan T, Gang Y, Baker L, Head AR, Waluyo I, Li R, Kisslinger K, Hunt A, Jarrige I, Lyon SA, Barbour AM, Cava RJ, Houck AA, Hulbert SL, Liu M, Walter AL, de Leon NP. Chemical Profiles of the Oxides on Tantalum in State of the Art Superconducting Circuits. Adv Sci (Weinh) 2023:e2300921. [PMID: 37166044 PMCID: PMC10375100 DOI: 10.1002/advs.202300921] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 04/27/2023] [Indexed: 05/12/2023]
Abstract
Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces. It is recently shown that replacing the metal in the capacitor of a transmon with tantalum yields record relaxation and coherence times for superconducting qubits, motivating a detailed study of the tantalum surface. In this work, the chemical profile of the surface of tantalum films grown on c-plane sapphire using variable energy X-ray photoelectron spectroscopy (VEXPS) is studied. The different oxidation states of tantalum that are present in the native oxide resulting from exposure to air are identified, and their distribution through the depth of the film is measured. Furthermore, it is shown how the volume and depth distribution of these tantalum oxidation states can be altered by various chemical treatments. Correlating these measurements with detailed measurements of quantum devices may elucidate the underlying microscopic sources of loss.
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Affiliation(s)
- Russell A McLellan
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Aveek Dutta
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Chenyu Zhou
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Yichen Jia
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Conan Weiland
- Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Xin Gui
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Alexander P M Place
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Kevin D Crowley
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Xuan Hoang Le
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Trisha Madhavan
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Youqi Gang
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Lukas Baker
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Ashley R Head
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Iradwikanari Waluyo
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Ruoshui Li
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Kim Kisslinger
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Adrian Hunt
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Ignace Jarrige
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Stephen A Lyon
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Andi M Barbour
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Robert J Cava
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Andrew A Houck
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Steven L Hulbert
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Mingzhao Liu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Bldg. 735, P.O. Box 5000, Upton, NY, 11973-5000, USA
| | - Andrew L Walter
- National Synchrotron Light Source II, Brookhaven National Laboratory, Bldg 740, Upton, NY, 11973-5000, USA
| | - Nathalie P de Leon
- Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, 08544, USA
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50
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Storz S, Schär J, Kulikov A, Magnard P, Kurpiers P, Lütolf J, Walter T, Copetudo A, Reuer K, Akin A, Besse JC, Gabureac M, Norris GJ, Rosario A, Martin F, Martinez J, Amaya W, Mitchell MW, Abellan C, Bancal JD, Sangouard N, Royer B, Blais A, Wallraff A. Loophole-free Bell inequality violation with superconducting circuits. Nature 2023; 617:265-270. [PMID: 37165240 PMCID: PMC10172133 DOI: 10.1038/s41586-023-05885-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/24/2023] [Indexed: 05/12/2023]
Abstract
Superposition, entanglement and non-locality constitute fundamental features of quantum physics. The fact that quantum physics does not follow the principle of local causality1-3 can be experimentally demonstrated in Bell tests4 performed on pairs of spatially separated, entangled quantum systems. Although Bell tests, which are widely regarded as a litmus test of quantum physics, have been explored using a broad range of quantum systems over the past 50 years, only relatively recently have experiments free of so-called loopholes5 succeeded. Such experiments have been performed with spins in nitrogen-vacancy centres6, optical photons7-9 and neutral atoms10. Here we demonstrate a loophole-free violation of Bell's inequality with superconducting circuits, which are a prime contender for realizing quantum computing technology11. To evaluate a Clauser-Horne-Shimony-Holt-type Bell inequality4, we deterministically entangle a pair of qubits12 and perform fast and high-fidelity measurements13 along randomly chosen bases on the qubits connected through a cryogenic link14 spanning a distance of 30 metres. Evaluating more than 1 million experimental trials, we find an average S value of 2.0747 ± 0.0033, violating Bell's inequality with a P value smaller than 10-108. Our work demonstrates that non-locality is a viable new resource in quantum information technology realized with superconducting circuits with potential applications in quantum communication, quantum computing and fundamental physics15.
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Affiliation(s)
- Simon Storz
- Department of Physics, ETH Zurich, Zurich, Switzerland.
| | - Josua Schär
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | | | - Paul Magnard
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Alice and Bob, Paris, France
| | - Philipp Kurpiers
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Rohde and Schwarz, Munich, Germany
| | - Janis Lütolf
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Theo Walter
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | - Adrian Copetudo
- Department of Physics, ETH Zurich, Zurich, Switzerland
- Centre for Quantum Technologies, National University of Singapore, Singapore, Singapore
| | - Kevin Reuer
- Department of Physics, ETH Zurich, Zurich, Switzerland
| | | | | | | | | | | | | | | | | | - Morgan W Mitchell
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
- ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | | | - Jean-Daniel Bancal
- Institute of Theoretical Physics, University of Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Nicolas Sangouard
- Institute of Theoretical Physics, University of Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Baptiste Royer
- Department of Physics, Yale University, New Haven, CT, USA
- Institut quantique and Départment de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Alexandre Blais
- Institut quantique and Départment de Physique, Université de Sherbrooke, Sherbrooke, Québec, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Andreas Wallraff
- Department of Physics, ETH Zurich, Zurich, Switzerland.
- Quantum Center, ETH Zurich, Zurich, Switzerland.
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