1
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Zhang X, Hu Z, Liu YC. Fast Generation of GHZ-like States Using Collective-Spin XYZ Model. PHYSICAL REVIEW LETTERS 2024; 132:113402. [PMID: 38563940 DOI: 10.1103/physrevlett.132.113402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/14/2024] [Indexed: 04/04/2024]
Abstract
The Greenberger-Horne-Zeilinger (GHZ) state is a key resource for quantum information processing and quantum metrology. The atomic GHZ state can be generated by one-axis twisting (OAT) interaction H_{OAT}=χJ_{z}^{2} with χ the interaction strength, but it requires a long evolution time χt=π/2 and is thus seriously influenced by decoherence and losses. Here we propose a three-body collective-spin XYZ model which creates a GHZ-like state in a very short timescale χt∼lnN/N for N particles. We show that this model can be effectively produced by applying Floquet driving to an original OAT Hamiltonian. Compared with the ideal GHZ state, the GHZ-like state generated using our model can maintain similar metrological properties reaching the Heisenberg-limited scaling, and it shows better robustness to decoherence and particle losses. This Letter opens the avenue for generating GHZ-like states with a large particle number, which holds great potential for the study of macroscopic quantum effects and for applications in quantum metrology and quantum information.
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Affiliation(s)
- Xuanchen Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zhiyao Hu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yong-Chun Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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2
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Butler EP, Fux GE, Ortega-Taberner C, Lovett BW, Keeling J, Eastham PR. Optimizing Performance of Quantum Operations with Non-Markovian Decoherence: The Tortoise or the Hare? PHYSICAL REVIEW LETTERS 2024; 132:060401. [PMID: 38394576 DOI: 10.1103/physrevlett.132.060401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 12/19/2023] [Indexed: 02/25/2024]
Abstract
The interaction between a quantum system and its environment limits our ability to control it and perform quantum operations on it. We present an efficient method to find optimal controls for quantum systems coupled to non-Markovian environments, by using the process tensor to compute the gradient of an objective function. We consider state transfer for a driven two-level system coupled to a bosonic environment, and characterize performance in terms of speed and fidelity. This allows us to determine the best achievable fidelity as a function of process duration. We show there can be a trade-off between speed and fidelity, and that slower processes can have higher fidelity by exploiting non-Markovian effects.
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Affiliation(s)
- Eoin P Butler
- School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland
- Trinity Quantum Alliance, Unit 16, Trinity Technology and Enterprise Centre, Pearse Street, Dublin 2, Ireland
| | - Gerald E Fux
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
- Abdus Salam International Center for Theoretical Physics (ICTP), Strada Costiera 11, 34151 Trieste, Italy
| | - Carlos Ortega-Taberner
- School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland
- Trinity Quantum Alliance, Unit 16, Trinity Technology and Enterprise Centre, Pearse Street, Dublin 2, Ireland
| | - Brendon W Lovett
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Jonathan Keeling
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Paul R Eastham
- School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland
- Trinity Quantum Alliance, Unit 16, Trinity Technology and Enterprise Centre, Pearse Street, Dublin 2, Ireland
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3
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Liu SC, Cheng L, Yao GZ, Wang YX, Peng LY. Efficient numerical approach to high-fidelity phase-modulated gates in long chains of trapped ions. Phys Rev E 2023; 107:035304. [PMID: 37072959 DOI: 10.1103/physreve.107.035304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 03/02/2023] [Indexed: 04/20/2023]
Abstract
Almost every quantum circuit is built with two-qubit gates in the current stage, which are crucial to the quantum computing in any platform. The entangling gates based on Mølmer-Sørensen schemes are widely exploited in the trapped-ion system, with the utilization of the collective motional modes of ions and two laser-controlled internal states, which are served as qubits. The key to realize high-fidelity and robust gates is the minimization of the entanglement between the qubits and the motional modes under various sources of errors after the gate operation. In this work, we propose an efficient numerical method to search high-quality solutions for phase-modulated pulses. Instead of directly optimizing a cost function, which contains the fidelity and the robustness of the gates, we convert the problem to the combination of linear algebra and the solution to quadratic equations. Once a solution with the gate fidelity of 1 is found, the laser power can be further reduced while searching on the manifold where the fidelity remains 1. Our method largely overcomes the problem of the convergence and is shown to be effective up to 60 ions, which suffices the need of the gate design in current trapped-ion experiments.
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Affiliation(s)
- Sheng-Chen Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871 Beijing, China
| | - Lin Cheng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871 Beijing, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Gui-Zhong Yao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871 Beijing, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Ying-Xiang Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871 Beijing, China
| | - Liang-You Peng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, 100871 Beijing, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006 Taiyuan, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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4
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Sauvage F, Mintert F. Optimal Control of Families of Quantum Gates. PHYSICAL REVIEW LETTERS 2022; 129:050507. [PMID: 35960583 DOI: 10.1103/physrevlett.129.050507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Quantum optimal control (QOC) enables the realization of accurate operations, such as quantum gates, and supports the development of quantum technologies. To date, many QOC frameworks have been developed, but those remain only naturally suited to optimize a single targeted operation at a time. We extend this concept to optimal control with a continuous family of targets, and demonstrate that an optimization based on neural networks can find families of time-dependent Hamiltonians realizing desired classes of quantum gates in minimal time.
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Affiliation(s)
- Frédéric Sauvage
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2BW, United Kingdom
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Florian Mintert
- Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, SW7 2BW, United Kingdom
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5
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Jiang Y, Cai ML, Wu YK, Mei QX, Zhao WD, Chang XY, Yao L, He L, Zhou ZC, Duan LM. Quantum Simulation of the Two-Dimensional Weyl Equation in a Magnetic Field. PHYSICAL REVIEW LETTERS 2022; 128:200502. [PMID: 35657866 DOI: 10.1103/physrevlett.128.200502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/25/2022] [Indexed: 06/15/2023]
Abstract
Quantum simulation of 1D relativistic quantum mechanics has been achieved in well-controlled systems like trapped ions, but properties like spin dynamics and response to external magnetic fields that appear only in higher dimensions remain unexplored. Here we simulate the dynamics of a 2D Weyl particle. We show the linear dispersion relation of the free particle and the discrete Landau levels in a magnetic field, and we explicitly measure the spatial and spin dynamics from which the conservation of helicity and properties of antiparticles can be verified. Our work extends the application of an ion trap quantum simulator in particle physics with the additional spatial and spin degrees of freedom.
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Affiliation(s)
- Y Jiang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - M-L Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Q-X Mei
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - W-D Zhao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - X-Y Chang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L Yao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - L He
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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6
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Francis A, Zhu D, Huerta Alderete C, Johri S, Xiao X, Freericks JK, Monroe C, Linke NM, Kemper AF. Many-body thermodynamics on quantum computers via partition function zeros. SCIENCE ADVANCES 2021; 7:7/34/eabf2447. [PMID: 34407938 PMCID: PMC8373169 DOI: 10.1126/sciadv.abf2447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Partition functions are ubiquitous in physics: They are important in determining the thermodynamic properties of many-body systems and in understanding their phase transitions. As shown by Lee and Yang, analytically continuing the partition function to the complex plane allows us to obtain its zeros and thus the entire function. Moreover, the scaling and nature of these zeros can elucidate phase transitions. Here, we show how to find partition function zeros on noisy intermediate-scale trapped-ion quantum computers in a scalable manner, using the XXZ spin chain model as a prototype, and observe their transition from XY-like behavior to Ising-like behavior as a function of the anisotropy. While quantum computers cannot yet scale to the thermodynamic limit, our work provides a pathway to do so as hardware improves, allowing the future calculation of critical phenomena for systems beyond classical computing limits.
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Affiliation(s)
- Akhil Francis
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Daiwei Zhu
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD 20742, USA
- Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - Cinthia Huerta Alderete
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD 20742, USA
- Instituto Nacional de Astrofísica, Óptica y Electrónica, Calle Luis Enrique Erro No. 1, Sta. Ma. Tonantzintla, Pue. CP 72840, Mexico
| | - Sonika Johri
- IonQ Inc., 4505 Campus Dr, College Park, MD 20740, USA
| | - Xiao Xiao
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - James K Freericks
- Department of Physics, Georgetown University, 37th and O Sts. NW, Washington, DC 20057, USA
| | - Christopher Monroe
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD 20742, USA
- Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
- IonQ Inc., 4505 Campus Dr, College Park, MD 20740, USA
| | - Norbert M Linke
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Alexander F Kemper
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
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7
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Milne AR, Hempel C, Li L, Edmunds CL, Slatyer HJ, Ball H, Hush MR, Biercuk MJ. Quantum Oscillator Noise Spectroscopy via Displaced Cat States. PHYSICAL REVIEW LETTERS 2021; 126:250506. [PMID: 34241523 DOI: 10.1103/physrevlett.126.250506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 04/21/2021] [Indexed: 06/13/2023]
Abstract
Quantum harmonic oscillators are central to many modern quantum technologies. We introduce a method to determine the frequency noise spectrum of oscillator modes through coupling them to a qubit with continuously driven qubit-state-dependent displacements. We reconstruct the noise spectrum using a series of different drive phase and amplitude modulation patterns in conjunction with a data-fusion routine based on convex optimization. We apply the technique to the identification of intrinsic noise in the motional frequency of a single trapped ion with sensitivity to fluctuations at the sub-Hz level in a spectral range from quasi-dc up to 50 kHz.
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Affiliation(s)
- Alistair R Milne
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | - Cornelius Hempel
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | - Li Li
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
| | - Claire L Edmunds
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
| | | | - Harrison Ball
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
| | | | - Michael J Biercuk
- ARC Centre of Excellence for Engineered Quantum Systems, The University of Sydney, School of Physics, New South Wales 2006, Australia
- Q-CTRL Pty Ltd, Sydney, New South Wales 2006, Australia
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8
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Blümel R, Grzesiak N, Nguyen NH, Green AM, Li M, Maksymov A, Linke NM, Nam Y. Efficient Stabilized Two-Qubit Gates on a Trapped-Ion Quantum Computer. PHYSICAL REVIEW LETTERS 2021; 126:220503. [PMID: 34152167 DOI: 10.1103/physrevlett.126.220503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
In order to scale up quantum processors and achieve a quantum advantage, it is crucial to economize on the power requirement of two-qubit gates, make them robust to drift in experimental parameters, and shorten the gate times. Applicable to all quantum computer architectures whose two-qubit gates rely on phase-space closure, we present here a new gate-optimizing principle according to which negligible amounts of gate fidelity are traded for substantial savings in power, which, in turn, can be traded for substantial increases in gate speed and/or qubit connectivity. As a concrete example, we illustrate the method by constructing optimal pulses for entangling gates on a pair of ions within a trapped-ion chain, one of the leading quantum computing architectures. Our method is direct, noniterative, and linear, and, in some parameter regimes, constructs gate-steering pulses requiring up to an order of magnitude less power than the standard method. Additionally, our method provides increased robustness to mode drift. We verify the new trade-off principle experimentally on our trapped-ion quantum computer.
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Affiliation(s)
- Reinhold Blümel
- Wesleyan University, Middletown, Connecticut 06459, USA
- IonQ, College Park, Maryland 20740, USA
| | | | - Nhung H Nguyen
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Alaina M Green
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Ming Li
- IonQ, College Park, Maryland 20740, USA
| | | | - Norbert M Linke
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Yunseong Nam
- IonQ, College Park, Maryland 20740, USA
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
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9
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Cai ML, Liu ZD, Zhao WD, Wu YK, Mei QX, Jiang Y, He L, Zhang X, Zhou ZC, Duan LM. Observation of a quantum phase transition in the quantum Rabi model with a single trapped ion. Nat Commun 2021; 12:1126. [PMID: 33602942 PMCID: PMC7893029 DOI: 10.1038/s41467-021-21425-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 01/22/2021] [Indexed: 11/30/2022] Open
Abstract
Quantum phase transitions (QPTs) are usually associated with many-body systems in the thermodynamic limit when their ground states show abrupt changes at zero temperature with variation of a parameter in the Hamiltonian. Recently it has been realized that a QPT can also occur in a system composed of only a two-level atom and a single-mode bosonic field, described by the quantum Rabi model (QRM). Here we report an experimental demonstration of a QPT in the QRM using a 171Yb+ ion in a Paul trap. We measure the spin-up state population and the average phonon number of the ion as two order parameters and observe clear evidence of the phase transition via adiabatic tuning of the coupling between the ion and its spatial motion. An experimental probe of the phase transition in a fundamental quantum optics model without imposing the thermodynamic limit opens up a window for controlled study of QPTs and quantum critical phenomena. Quantum phase transition occurs in many-body systems with abrupt changes in the ground state around zero temperature. Here the authors report signatures of quantum phase transition in single trapped ion that can be described using quantum Rabi model.
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Affiliation(s)
- M-L Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - Z-D Liu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - W-D Zhao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - Q-X Mei
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - Y Jiang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - L He
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China
| | - X Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China.,Department of Physics, Renmin University, Beijing, PR China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China.,Beijing Academy of Quantum Information Sciences, Beijing, PR China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China.
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10
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Quantum walks and Dirac cellular automata on a programmable trapped-ion quantum computer. Nat Commun 2020; 11:3720. [PMID: 32709855 PMCID: PMC7381638 DOI: 10.1038/s41467-020-17519-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 07/02/2020] [Indexed: 11/08/2022] Open
Abstract
The quantum walk formalism is a widely used and highly successful framework for modeling quantum systems, such as simulations of the Dirac equation, different dynamics in both the low and high energy regime, and for developing a wide range of quantum algorithms. Here we present the circuit-based implementation of a discrete-time quantum walk in position space on a five-qubit trapped-ion quantum processor. We encode the space of walker positions in particular multi-qubit states and program the system to operate with different quantum walk parameters, experimentally realizing a Dirac cellular automaton with tunable mass parameter. The quantum walk circuits and position state mapping scale favorably to a larger model and physical systems, allowing the implementation of any algorithm based on discrete-time quantum walks algorithm and the dynamics associated with the discretized version of the Dirac equation.
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11
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Grzesiak N, Blümel R, Wright K, Beck KM, Pisenti NC, Li M, Chaplin V, Amini JM, Debnath S, Chen JS, Nam Y. Efficient arbitrary simultaneously entangling gates on a trapped-ion quantum computer. Nat Commun 2020; 11:2963. [PMID: 32528164 PMCID: PMC7289877 DOI: 10.1038/s41467-020-16790-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 05/26/2020] [Indexed: 11/25/2022] Open
Abstract
Efficiently entangling pairs of qubits is essential to fully harness the power of quantum computing. Here, we devise an exact protocol that simultaneously entangles arbitrary pairs of qubits on a trapped-ion quantum computer. The protocol requires classical computational resources polynomial in the system size, and very little overhead in the quantum control compared to a single-pair case. We demonstrate an exponential improvement in both classical and quantum resources over the current state of the art. We implement the protocol on a software-defined trapped-ion quantum computer, where we reconfigure the quantum computer architecture on demand. Our protocol may also be extended to a wide variety of other quantum computing platforms. Here, the authors devise an exact protocol that simultaneously entangles arbitrary pairs of qubits on a trapped-ion quantum computer. The protocol requires classical computational resources polynomial in the system size, and very little overhead in the quantum control compared to a single-pair case.
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Affiliation(s)
| | - Reinhold Blümel
- IonQ, College Park, MD, 20740, USA. .,Wesleyan University, Middletown, CT, 06459, USA.
| | | | | | | | - Ming Li
- IonQ, College Park, MD, 20740, USA
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12
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13
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Zarantonello G, Hahn H, Morgner J, Schulte M, Bautista-Salvador A, Werner RF, Hammerer K, Ospelkaus C. Robust and Resource-Efficient Microwave Near-Field Entangling ^{9}Be^{+} Gate. PHYSICAL REVIEW LETTERS 2019; 123:260503. [PMID: 31951443 DOI: 10.1103/physrevlett.123.260503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Indexed: 06/10/2023]
Abstract
Microwave trapped-ion quantum logic gates avoid spontaneous emission as a fundamental source of decoherence. However, microwave two-qubit gates are still slower than laser-induced gates and hence more sensitive to fluctuations and noise of the motional mode frequency. We propose and implement amplitude-shaped gate drives to obtain resilience to such frequency changes without increasing the pulse energy per gate operation. We demonstrate the resilience by noise injection during a two-qubit entangling gate with ^{9}Be^{+} ion qubits. In the absence of injected noise, amplitude modulation gives an operation infidelity in the 10^{-3} range.
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Affiliation(s)
- G Zarantonello
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - H Hahn
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - J Morgner
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - M Schulte
- Institut für Theoretische Physik und Institut für Gravitationsphysik (Albert-Einstein-Institut), Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - A Bautista-Salvador
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
- Laboratorium für Nano- und Quantenengineering, Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
| | - R F Werner
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - K Hammerer
- Institut für Theoretische Physik und Institut für Gravitationsphysik (Albert-Einstein-Institut), Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany
| | - C Ospelkaus
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
- Laboratorium für Nano- und Quantenengineering, Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
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14
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Wright K, Beck KM, Debnath S, Amini JM, Nam Y, Grzesiak N, Chen JS, Pisenti NC, Chmielewski M, Collins C, Hudek KM, Mizrahi J, Wong-Campos JD, Allen S, Apisdorf J, Solomon P, Williams M, Ducore AM, Blinov A, Kreikemeier SM, Chaplin V, Keesan M, Monroe C, Kim J. Benchmarking an 11-qubit quantum computer. Nat Commun 2019; 10:5464. [PMID: 31784527 PMCID: PMC6884641 DOI: 10.1038/s41467-019-13534-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/13/2019] [Indexed: 11/23/2022] Open
Abstract
The field of quantum computing has grown from concept to demonstration devices over the past 20 years. Universal quantum computing offers efficiency in approaching problems of scientific and commercial interest, such as factoring large numbers, searching databases, simulating intractable models from quantum physics, and optimizing complex cost functions. Here, we present an 11-qubit fully-connected, programmable quantum computer in a trapped ion system composed of 13 171Yb+ ions. We demonstrate average single-qubit gate fidelities of 99.5\documentclass[12pt]{minimal}
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\begin{document}$$\%$$\end{document}%, respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware. The growing complexity of quantum computing devices makes presents challenges for benchmarking their performance as previous, exhaustive approaches become infeasible. Here the authors characterise the quality of their 11-qubit device by successfully computing two quantum algorithms.
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Affiliation(s)
- K Wright
- IonQ, Inc., College Park, MD, 20740, USA.
| | - K M Beck
- IonQ, Inc., College Park, MD, 20740, USA
| | - S Debnath
- IonQ, Inc., College Park, MD, 20740, USA
| | - J M Amini
- IonQ, Inc., College Park, MD, 20740, USA
| | - Y Nam
- IonQ, Inc., College Park, MD, 20740, USA
| | - N Grzesiak
- IonQ, Inc., College Park, MD, 20740, USA
| | - J-S Chen
- IonQ, Inc., College Park, MD, 20740, USA
| | | | - M Chmielewski
- IonQ, Inc., College Park, MD, 20740, USA.,Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - C Collins
- IonQ, Inc., College Park, MD, 20740, USA
| | - K M Hudek
- IonQ, Inc., College Park, MD, 20740, USA
| | - J Mizrahi
- IonQ, Inc., College Park, MD, 20740, USA
| | | | - S Allen
- IonQ, Inc., College Park, MD, 20740, USA
| | - J Apisdorf
- IonQ, Inc., College Park, MD, 20740, USA
| | - P Solomon
- IonQ, Inc., College Park, MD, 20740, USA
| | - M Williams
- IonQ, Inc., College Park, MD, 20740, USA
| | - A M Ducore
- IonQ, Inc., College Park, MD, 20740, USA
| | - A Blinov
- IonQ, Inc., College Park, MD, 20740, USA
| | | | - V Chaplin
- IonQ, Inc., College Park, MD, 20740, USA
| | - M Keesan
- IonQ, Inc., College Park, MD, 20740, USA
| | - C Monroe
- IonQ, Inc., College Park, MD, 20740, USA.,Joint Quantum Institute and Department of Physics, University of Maryland, College Park, MD, 20742, USA
| | - J Kim
- IonQ, Inc., College Park, MD, 20740, USA.,Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708, USA
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15
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Zhu D, Linke NM, Benedetti M, Landsman KA, Nguyen NH, Alderete CH, Perdomo-Ortiz A, Korda N, Garfoot A, Brecque C, Egan L, Perdomo O, Monroe C. Training of quantum circuits on a hybrid quantum computer. SCIENCE ADVANCES 2019; 5:eaaw9918. [PMID: 31667342 PMCID: PMC6799983 DOI: 10.1126/sciadv.aaw9918] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 09/26/2019] [Indexed: 05/28/2023]
Abstract
Generative modeling is a flavor of machine learning with applications ranging from computer vision to chemical design. It is expected to be one of the techniques most suited to take advantage of the additional resources provided by near-term quantum computers. Here, we implement a data-driven quantum circuit training algorithm on the canonical Bars-and-Stripes dataset using a quantum-classical hybrid machine. The training proceeds by running parameterized circuits on a trapped ion quantum computer and feeding the results to a classical optimizer. We apply two separate strategies, Particle Swarm and Bayesian optimization to this task. We show that the convergence of the quantum circuit to the target distribution depends critically on both the quantum hardware and classical optimization strategy. Our study represents the first successful training of a high-dimensional universal quantum circuit and highlights the promise and challenges associated with hybrid learning schemes.
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Affiliation(s)
- D. Zhu
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - N. M. Linke
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - M. Benedetti
- Department of Computer Science, University College London, WC1E 6BT London, UK
- Cambridge Quantum Computing Limited, CB2 1UB Cambridge, UK
| | - K. A. Landsman
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - N. H. Nguyen
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - C. H. Alderete
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - A. Perdomo-Ortiz
- Department of Computer Science, University College London, WC1E 6BT London, UK
- Zapata Computing Inc., 439 University Avenue, Office 535, Toronto, ON, M5G 1Y8, Canada
| | - N. Korda
- Mind Foundry Limited, OX2 7DD Oxford, UK
| | - A. Garfoot
- Mind Foundry Limited, OX2 7DD Oxford, UK
| | - C. Brecque
- Mind Foundry Limited, OX2 7DD Oxford, UK
| | - L. Egan
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
| | - O. Perdomo
- Department of Mathematics, Central Connecticut State University, New Britain, CT 06050, USA
| | - C. Monroe
- Joint Quantum Institute, Department of Physics, and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA
- IonQ Inc., College Park, MD 20740, USA
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16
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Lu Y, Zhang S, Zhang K, Chen W, Shen Y, Zhang J, Zhang JN, Kim K. Global entangling gates on arbitrary ion qubits. Nature 2019; 572:363-367. [PMID: 31341282 DOI: 10.1038/s41586-019-1428-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/10/2019] [Indexed: 11/09/2022]
Abstract
Quantum computers can efficiently solve classically intractable problems, such as the factorization of a large number1 and the simulation of quantum many-body systems2,3. Universal quantum computation can be simplified by decomposing circuits into single- and two-qubit entangling gates4, but such decomposition is not necessarily efficient. It has been suggested that polynomial or exponential speedups can be obtained with global N-qubit (N greater than two) entangling gates5-9. Such global gates involve all-to-all connectivity, which emerges among trapped-ion qubits when using laser-driven collective motional modes10-14, and have been implemented for a single motional mode15,16. However, the single-mode approach is difficult to scale up because isolating single modes becomes challenging as the number of ions increases in a single crystal, and multi-mode schemes are scalable17,18 but limited to pairwise gates19-23. Here we propose and implement a scalable scheme for realizing global entangling gates on multiple 171Yb+ ion qubits by coupling to multiple motional modes through modulated laser fields. Because such global gates require decoupling multiple modes and balancing all pairwise coupling strengths during the gate, we develop a system with fully independent control capability on each ion14. To demonstrate the usefulness and flexibility of these global gates, we generate a Greenberger-Horne-Zeilinger state with up to four qubits using a single global operation. Our approach realizes global entangling gates as scalable building blocks for universal quantum computation, motivating future research in scalable global methods for quantum information processing.
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Affiliation(s)
- Yao Lu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China.
| | - Shuaining Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Kuan Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China.,MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan, China
| | - Wentao Chen
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Yangchao Shen
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Jialiang Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Jing-Ning Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Kihwan Kim
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China.
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17
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Parallel entangling operations on a universal ion-trap quantum computer. Nature 2019; 572:368-372. [DOI: 10.1038/s41586-019-1427-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 06/03/2019] [Indexed: 11/08/2022]
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18
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Landsman KA, Figgatt C, Schuster T, Linke NM, Yoshida B, Yao NY, Monroe C. Verified quantum information scrambling. Nature 2019; 567:61-65. [DOI: 10.1038/s41586-019-0952-6] [Citation(s) in RCA: 152] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 01/08/2019] [Indexed: 11/09/2022]
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19
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Ge W, Sawyer BC, Britton JW, Jacobs K, Bollinger JJ, Foss-Feig M. Trapped Ion Quantum Information Processing with Squeezed Phonons. PHYSICAL REVIEW LETTERS 2019; 122:030501. [PMID: 30735427 DOI: 10.1103/physrevlett.122.030501] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Indexed: 06/09/2023]
Abstract
Trapped ions offer a pristine platform for quantum computation and simulation, but improving their coherence remains a crucial challenge. Here, we propose and analyze a new strategy to enhance the coherent interactions in trapped ion systems via parametric amplification of the ions' motion-by squeezing the collective motional modes (phonons), the spin-spin interactions they mediate can be significantly enhanced. We illustrate the power of this approach by showing how it can enhance collective spin states useful for quantum metrology, and how it can improve the speed and fidelity of two-qubit gates in multi-ion systems, important ingredients for scalable trapped ion quantum computation. Our results are also directly relevant to numerous other physical platforms in which spin interactions are mediated by bosons.
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Affiliation(s)
- Wenchao Ge
- United States Army Research Laboratory, Adelphi, Maryland 20783, USA
- The Institute for Research in Electronics and Applied Physics (IREAP), College Park, Maryland 20740, USA
| | - Brian C Sawyer
- Georgia Tech Research Institute, Atlanta, Georgia 30332, USA
| | - Joseph W Britton
- United States Army Research Laboratory, Adelphi, Maryland 20783, USA
| | - Kurt Jacobs
- United States Army Research Laboratory, Adelphi, Maryland 20783, USA
- Department of Physics, University of Massachusetts at Boston, Boston, Massachusetts 02125, USA
- Hearne Institute for Theoretical Physics, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - John J Bollinger
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Michael Foss-Feig
- United States Army Research Laboratory, Adelphi, Maryland 20783, USA
- Joint Quantum Institute, NIST/University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742, USA
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20
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Leung PH, Landsman KA, Figgatt C, Linke NM, Monroe C, Brown KR. Robust 2-Qubit Gates in a Linear Ion Crystal Using a Frequency-Modulated Driving Force. PHYSICAL REVIEW LETTERS 2018; 120:020501. [PMID: 29376710 DOI: 10.1103/physrevlett.120.020501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/30/2017] [Indexed: 06/07/2023]
Abstract
In an ion trap quantum computer, collective motional modes are used to entangle two or more qubits in order to execute multiqubit logical gates. Any residual entanglement between the internal and motional states of the ions results in loss of fidelity, especially when there are many spectator ions in the crystal. We propose using a frequency-modulated driving force to minimize such errors. In simulation, we obtained an optimized frequency-modulated 2-qubit gate that can suppress errors to less than 0.01% and is robust against frequency drifts over ±1 kHz. Experimentally, we have obtained a 2-qubit gate fidelity of 98.3(4)%, a state-of-the-art result for 2-qubit gates with five ions.
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Affiliation(s)
- Pak Hong Leung
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Kevin A Landsman
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Caroline Figgatt
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Norbert M Linke
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Christopher Monroe
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
- IonQ Inc., College Park, Maryland 20742, USA
| | - Kenneth R Brown
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Schools of Chemistry and Biochemistry and Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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21
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Zopes J, Sasaki K, Cujia KS, Boss JM, Chang K, Segawa TF, Itoh KM, Degen CL. High-Resolution Quantum Sensing with Shaped Control Pulses. PHYSICAL REVIEW LETTERS 2017; 119:260501. [PMID: 29328731 DOI: 10.1103/physrevlett.119.260501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Indexed: 06/07/2023]
Abstract
We investigate the application of amplitude-shaped control pulses for enhancing the time and frequency resolution of multipulse quantum sensing sequences. Using the electronic spin of a single nitrogen-vacancy center in diamond and up to 10 000 coherent microwave pulses with a cosine square envelope, we demonstrate 0.6-ps timing resolution for the interpulse delay. This represents a refinement by over 3 orders of magnitude compared to the 2-ns hardware sampling. We apply the method for the detection of external ac magnetic fields and nuclear magnetic resonance signals of ^{13}C spins with high spectral resolution. Our method is simple to implement and especially useful for quantum applications that require fast phase gates, many control pulses, and high fidelity.
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Affiliation(s)
- J Zopes
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - K Sasaki
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - K S Cujia
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - J M Boss
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - K Chang
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - T F Segawa
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - C L Degen
- Department of Physics, ETH Zurich, Otto Stern Weg 1, 8093 Zurich, Switzerland
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22
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Complete 3-Qubit Grover search on a programmable quantum computer. Nat Commun 2017; 8:1918. [PMID: 29203858 PMCID: PMC5715115 DOI: 10.1038/s41467-017-01904-7] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 10/25/2017] [Indexed: 11/17/2022] Open
Abstract
The Grover quantum search algorithm is a hallmark application of a quantum computer with a well-known speedup over classical searches of an unsorted database. Here, we report results for a complete three-qubit Grover search algorithm using the scalable quantum computing technology of trapped atomic ions, with better-than-classical performance. Two methods of state marking are used for the oracles: a phase-flip method employed by other experimental demonstrations, and a Boolean method requiring an ancilla qubit that is directly equivalent to the state marking scheme required to perform a classical search. We also report the deterministic implementation of a Toffoli-4 gate, which is used along with Toffoli-3 gates to construct the algorithms; these gates have process fidelities of 70.5% and 89.6%, respectively. Grover’s algorithm provides a quantum speedup when searching through an unsorted database. Here, the authors perform it on 3 qubits using trapped ions, demonstrating two methods for marking the correct result in the algorithm’s oracle and providing data for searches yielding 1 or 2 solutions.
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23
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Linke NM, Gutierrez M, Landsman KA, Figgatt C, Debnath S, Brown KR, Monroe C. Fault-tolerant quantum error detection. SCIENCE ADVANCES 2017; 3:e1701074. [PMID: 29062889 PMCID: PMC5650489 DOI: 10.1126/sciadv.1701074] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 09/21/2017] [Indexed: 05/22/2023]
Abstract
Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. This redundancy allows the extraction of error syndromes and the subsequent detection or correction of errors without destroying the logical state itself through direct measurement. We show the encoding and syndrome measurement of a fault-tolerantly prepared logical qubit via an error detection protocol on four physical qubits, represented by trapped atomic ions. This demonstrates the robustness of a logical qubit to imperfections in the very operations used to encode it. The advantage persists in the face of large added error rates and experimental calibration errors.
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Affiliation(s)
- Norbert M. Linke
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Mauricio Gutierrez
- Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kevin A. Landsman
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Caroline Figgatt
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Shantanu Debnath
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
| | - Kenneth R. Brown
- Schools of Chemistry and Biochemistry, Computational Science and Engineering, and Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Christopher Monroe
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, MD 20742, USA
- IonQ Inc., College Park, MD 20742, USA
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24
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Abstract
We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device (www. RESEARCH ibm.com/ibm-q) with limited connectivity, and the other is a fully connected trapped-ion system. Even though the two systems have different native quantum interactions, both can be programed in a way that is blind to the underlying hardware, thus allowing a comparison of identical quantum algorithms between different physical systems. We show that quantum algorithms and circuits that use more connectivity clearly benefit from a better-connected system of qubits. Although the quantum systems here are not yet large enough to eclipse classical computers, this experiment exposes critical factors of scaling quantum computers, such as qubit connectivity and gate expressivity. In addition, the results suggest that codesigning particular quantum applications with the hardware itself will be paramount in successfully using quantum computers in the future.
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25
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Demonstration of a small programmable quantum computer with atomic qubits. Nature 2016; 536:63-6. [DOI: 10.1038/nature18648] [Citation(s) in RCA: 435] [Impact Index Per Article: 54.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/01/2016] [Indexed: 11/08/2022]
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26
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Las Heras U, Alvarez-Rodriguez U, Solano E, Sanz M. Genetic Algorithms for Digital Quantum Simulations. PHYSICAL REVIEW LETTERS 2016; 116:230504. [PMID: 27341220 DOI: 10.1103/physrevlett.116.230504] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Indexed: 06/06/2023]
Abstract
We propose genetic algorithms, which are robust optimization techniques inspired by natural selection, to enhance the versatility of digital quantum simulations. In this sense, we show that genetic algorithms can be employed to increase the fidelity and optimize the resource requirements of digital quantum simulation protocols while adapting naturally to the experimental constraints. Furthermore, this method allows us to reduce not only digital errors but also experimental errors in quantum gates. Indeed, by adding ancillary qubits, we design a modular gate made out of imperfect gates, whose fidelity is larger than the fidelity of any of the constituent gates. Finally, we prove that the proposed modular gates are resilient against different gate errors.
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Affiliation(s)
- U Las Heras
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - U Alvarez-Rodriguez
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - E Solano
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48011 Bilbao, Spain
| | - M Sanz
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
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27
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Schulte M, Lörch N, Leroux ID, Schmidt PO, Hammerer K. Quantum Algorithmic Readout in Multi-Ion Clocks. PHYSICAL REVIEW LETTERS 2016; 116:013002. [PMID: 26799016 DOI: 10.1103/physrevlett.116.013002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 06/05/2023]
Abstract
Optical clocks based on ensembles of trapped ions promise record frequency accuracy with good short-term stability. Most suitable ion species lack closed transitions, so the clock signal must be read out indirectly by transferring the quantum state of the clock ions to cotrapped logic ions of a different species. Existing methods of quantum logic readout require a linear overhead in either time or the number of logic ions. Here we describe a quantum algorithmic readout whose overhead scales logarithmically with the number of clock ions in both of these respects. The scheme allows a quantum nondemolition readout of the number of excited clock ions using a single multispecies gate operation which can also be used in other areas of ion trap technology such as quantum information processing, quantum simulations, metrology, and precision spectroscopy.
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Affiliation(s)
- M Schulte
- Institute for Theoretical Physics and Institute for Gravitational Physics (Albert-Einstein-Institute), Leibniz University Hannover, Callinstrasse 38, 30167 Hannover, Germany
| | - N Lörch
- Institute for Theoretical Physics and Institute for Gravitational Physics (Albert-Einstein-Institute), Leibniz University Hannover, Callinstrasse 38, 30167 Hannover, Germany
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - I D Leroux
- QUEST Institut, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - P O Schmidt
- QUEST Institut, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
- Institute for Quantum Optics, Leibniz University Hannover, Welfengarten 1, 30167 Hannover, Germany
| | - K Hammerer
- Institute for Theoretical Physics and Institute for Gravitational Physics (Albert-Einstein-Institute), Leibniz University Hannover, Callinstrasse 38, 30167 Hannover, Germany
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28
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Green TJ, Biercuk MJ. Phase-modulated decoupling and error suppression in qubit-oscillator systems. PHYSICAL REVIEW LETTERS 2015; 114:120502. [PMID: 25860726 DOI: 10.1103/physrevlett.114.120502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Indexed: 06/04/2023]
Abstract
We present a scheme designed to suppress the dominant source of infidelity in entangling gates between quantum systems coupled through intermediate bosonic oscillator modes. Such systems are particularly susceptible to residual qubit-oscillator entanglement at the conclusion of a gate period that reduces the fidelity of the target entangling operation. We demonstrate how the exclusive use of discrete shifts in the phase of the field moderating the qubit-oscillator interaction is sufficient to both ensure multiple oscillator modes are decoupled and to suppress the effects of fluctuations in the driving field. This approach is amenable to a wide variety of technical implementations including geometric phase gates in superconducting qubits and the Molmer-Sorensen gate for trapped ions. We present detailed example protocols tailored to trapped-ion experiments and demonstrate that our approach has the potential to enable multiqubit gate implementation with a significant reduction in technical complexity relative to previously demonstrated protocols.
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Affiliation(s)
- Todd J Green
- ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, New South Wales 2006 Australia
| | - Michael J Biercuk
- ARC Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, New South Wales 2006 Australia
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29
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Quantum computation under micromotion in a planar ion crystal. Sci Rep 2015; 5:8555. [PMID: 25711774 PMCID: PMC4339801 DOI: 10.1038/srep08555] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/23/2015] [Indexed: 11/11/2022] Open
Abstract
We propose a scheme to realize scalable quantum computation in a planar ion crystal confined by a Paul trap. We show that the inevitable in-plane micromotion affects the gate design via three separate effects: renormalization of the equilibrium positions, coupling to the transverse motional modes, and amplitude modulation in the addressing beam. We demonstrate that all of these effects can be taken into account and high-fidelity gates are possible in the presence of micromotion. This proposal opens the prospect to realize large-scale fault-tolerant quantum computation within a single Paul trap.
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30
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Barends R, Kelly J, Megrant A, Veitia A, Sank D, Jeffrey E, White TC, Mutus J, Fowler AG, Campbell B, Chen Y, Chen Z, Chiaro B, Dunsworth A, Neill C, O’Malley P, Roushan P, Vainsencher A, Wenner J, Korotkov AN, Cleland AN, Martinis JM. Superconducting quantum circuits at the surface code threshold for fault tolerance. Nature 2014; 508:500-3. [DOI: 10.1038/nature13171] [Citation(s) in RCA: 1057] [Impact Index Per Article: 105.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/24/2014] [Indexed: 11/09/2022]
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31
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