51
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Maleki Y, Zheltikov AM. A high-N00N output of harmonically driven cavity QED. Sci Rep 2019; 9:16780. [PMID: 31727904 PMCID: PMC6856350 DOI: 10.1038/s41598-019-49465-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/22/2019] [Indexed: 11/25/2022] Open
Abstract
A harmonically driven cavity QED system consisting of two cavities and a two-level qubit is shown to enable the generation of a vast class of maximally entangled states suitable for measurements with a Heisenberg-limit precision. As one of its modalities, this system can serve as a quantum beam splitter, converting an |N〉 ⊗ |0〉 input into a maximally entangled N00N state (|N〉 ⊗ |0〉 + |0〉 ⊗ |N〉)/\documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{{\bf{2}}}$$\end{document}2 at its output. A network of such quantum beam splitters is shown to provide a source of multimode N00N-type entanglement.
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Affiliation(s)
- Yusef Maleki
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas, 77843-4242, USA.
| | - Aleksei M Zheltikov
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas, 77843-4242, USA.,Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow, 119992, Russia.,Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 143025, Russia.,National University of Science and Technology "MISiS", Leninskii pr. 4, Moscow, 119049, Russia
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52
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Joo J, Lee CW, Kono S, Kim J. Logical measurement-based quantum computation in circuit-QED. Sci Rep 2019; 9:16592. [PMID: 31719588 PMCID: PMC6851091 DOI: 10.1038/s41598-019-52866-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/03/2019] [Indexed: 11/27/2022] Open
Abstract
We propose a new scheme of measurement-based quantum computation (MBQC) using an error-correcting code against photon-loss in circuit quantum electrodynamics. We describe a specific protocol of logical single-qubit gates given by sequential cavity measurements for logical MBQC and a generalised Schrödinger cat state is used for a continuous-variable (CV) logical qubit captured in a microwave cavity. To apply an error-correcting scheme on the logical qubit, we utilise a d-dimensional quantum system called a qudit. It is assumed that a three CV-qudit entangled state is initially prepared in three jointed cavities and the microwave qudit states are individually controlled, operated, and measured through a readout resonator coupled with an ancillary superconducting qubit. We then examine a practical approach of how to create the CV-qudit cluster state via a cross-Kerr interaction induced by intermediary superconducting qubits between neighbouring cavities under the Jaynes-Cummings Hamiltonian. This approach could be scalable for building 2D logical cluster states and therefore will pave a new pathway of logical MBQC in superconducting circuits toward fault-tolerant quantum computing.
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Affiliation(s)
- Jaewoo Joo
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea.
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK.
| | - Chang-Woo Lee
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea
- Department of Physics Education, Kongju National University, Gongju, 32588, South Korea
| | - Shingo Kono
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo, 153-8904, Japan
| | - Jaewan Kim
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea
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53
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Assemat F, Grosso D, Signoles A, Facon A, Dotsenko I, Haroche S, Raimond JM, Brune M, Gleyzes S. Quantum Rabi Oscillations in Coherent and in Mesoscopic Cat Field States. PHYSICAL REVIEW LETTERS 2019; 123:143605. [PMID: 31702170 DOI: 10.1103/physrevlett.123.143605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 06/10/2023]
Abstract
The simple resonant Rabi oscillation of a two-level system in a single-mode coherent field reveals complex features at the mesoscopic scale, with oscillation collapses and revivals. Using slow circular Rydberg atoms interacting with a superconducting microwave cavity, we explore this phenomenon in an unprecedented range of interaction times and photon numbers. We demonstrate the efficient production of cat states, which are the quantum superposition of coherent components with nearly opposite phases and sizes in the range of few tens of photons. We measure cuts of their Wigner functions revealing their quantum coherence and observe their fast decoherence. This experiment opens promising perspectives for the rapid generation and manipulation of nonclassical states in cavity and circuit quantum electrodynamics.
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Affiliation(s)
- F Assemat
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - D Grosso
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - A Signoles
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - A Facon
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - I Dotsenko
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - S Haroche
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - J M Raimond
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - M Brune
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
| | - S Gleyzes
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-Université PSL, Sorbonne Université, 11, place Marcelin Berthelot, 75005 Paris, France
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54
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Liu T, Zhang Y, Guo BQ, Yu CS, Zhang WN. Creation of superposition of arbitrary states encoded in two high-Q cavities. OPTICS EXPRESS 2019; 27:27168-27182. [PMID: 31674583 DOI: 10.1364/oe.27.027168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
The principle of superposition is a key ingredient for quantum mechanics. A recent work [Phys. Rev. Lett.116, 110403 (2016)10.1103/PhysRevLett.116.110403] has shown that a quantum adder that deterministically generates a superposition of two unknown states is forbidden. Here we consider the implementation of the probabilistic quantum adder in the 3D cavity-transmon system. Our implementation is based on a three-level superconducting transmon qubit dispersively coupled to two cavities. Numerical simulations show that high-fidelity generation of the superposition of two coherent states is feasible with current circuit QED technology. Our method also works for other physical systems such as two optical cavities coupled to a three-level atom or two nitrogen-vacancy center ensembles interacted with one three-level superconducting flux qubit.
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55
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Arrangoiz-Arriola P, Wollack EA, Wang Z, Pechal M, Jiang W, McKenna TP, Witmer JD, Van Laer R, Safavi-Naeini AH. Resolving the energy levels of a nanomechanical oscillator. Nature 2019; 571:537-540. [PMID: 31341303 DOI: 10.1038/s41586-019-1386-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 06/04/2019] [Indexed: 11/09/2022]
Abstract
The quantum nature of an oscillating mechanical object is anything but apparent. The coherent states that describe the classical motion of a mechanical oscillator do not have a well defined energy, but are quantum superpositions of equally spaced energy eigenstates. Revealing this quantized structure is only possible with an apparatus that measures energy with a precision greater than the energy of a single phonon. One way to achieve this sensitivity is by engineering a strong but nonresonant interaction between the oscillator and an atom. In a system with sufficient quantum coherence, this interaction allows one to distinguish different energy eigenstates using resolvable differences in the atom's transition frequency. For photons, such dispersive measurements have been performed in cavity1,2 and circuit quantum electrodynamics3. Here we report an experiment in which an artificial atom senses the motional energy of a driven nanomechanical oscillator with sufficient sensitivity to resolve the quantization of its energy. To realize this, we build a hybrid platform that integrates nanomechanical piezoelectric resonators with a microwave superconducting qubit on the same chip. We excite phonons with resonant pulses and probe the resulting excitation spectrum of the qubit to observe phonon-number-dependent frequency shifts that are about five times larger than the qubit linewidth. Our result demonstrates a fully integrated platform for quantum acoustics that combines large couplings, considerable coherence times and excellent control over the mechanical mode structure. With modest experimental improvements, we expect that our approach will enable quantum nondemolition measurements of phonons4 and will lead to quantum sensors and information-processing approaches5 that use chip-scale nanomechanical devices.
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Affiliation(s)
- Patricio Arrangoiz-Arriola
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - E Alex Wollack
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Zhaoyou Wang
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Marek Pechal
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Wentao Jiang
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Timothy P McKenna
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Jeremy D Witmer
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Raphaël Van Laer
- Department of Applied Physics, Stanford University, Stanford, CA, USA.,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - Amir H Safavi-Naeini
- Department of Applied Physics, Stanford University, Stanford, CA, USA. .,E. L. Ginzton Laboratory, Stanford University, Stanford, CA, USA.
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56
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Lee M, Friebe K, Fioretto DA, Schüppert K, Ong FR, Plankensteiner D, Torggler V, Ritsch H, Blatt R, Northup TE. Ion-Based Quantum Sensor for Optical Cavity Photon Numbers. PHYSICAL REVIEW LETTERS 2019; 122:153603. [PMID: 31050508 DOI: 10.1103/physrevlett.122.153603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Indexed: 06/09/2023]
Abstract
We dispersively couple a single trapped ion to an optical cavity to extract information about the cavity photon-number distribution in a nondestructive way. The photon-number-dependent ac Stark shift experienced by the ion is measured via Ramsey spectroscopy. We use these measurements first to obtain the ion-cavity interaction strength. Next, we reconstruct the cavity photon-number distribution for coherent states and for a state with mixed thermal-coherent statistics, finding overlaps above 99% with the calibrated states.
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Affiliation(s)
- Moonjoo Lee
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Konstantin Friebe
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Dario A Fioretto
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Klemens Schüppert
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Florian R Ong
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - David Plankensteiner
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21 a, 6020 Innsbruck, Austria
| | - Valentin Torggler
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21 a, 6020 Innsbruck, Austria
| | - Helmut Ritsch
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21 a, 6020 Innsbruck, Austria
| | - Rainer Blatt
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - Tracy E Northup
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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57
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Lebreuilly J, Aron C, Mora C. Stabilizing Arrays of Photonic Cat States via Spontaneous Symmetry Breaking. PHYSICAL REVIEW LETTERS 2019; 122:120402. [PMID: 30978066 DOI: 10.1103/physrevlett.122.120402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Indexed: 06/09/2023]
Abstract
The controlled generation and the protection of entanglement is key to quantum simulation and quantum computation. At the single-mode level, protocols based on photonic cat states hold strong promise as they present unprecedentedly long-lived coherence and may be combined with powerful error correction schemes. Here, we demonstrate that robust ensembles of "many-body photonic cat states" can be generated in a Bose-Hubbard model with pair hopping via a spontaneous U(1) symmetry-breaking mechanism. We identify a parameter region where the ground state is a massively degenerate manifold consisting of local cat states which are factorized throughout the lattice and whose conserved individual parities can be used to make a register of qubits. This phenomenology occurs for arbitrary system sizes or geometries, as soon as long-range order is established, and it extends to driven-dissipative conditions. In the thermodynamic limit, it is related to a Mott insulator to pair-superfluid phase transition.
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Affiliation(s)
- José Lebreuilly
- Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Université, Université Paris Diderot-Sorbonne Paris Cité, Paris 75005, France
| | - Camille Aron
- Laboratoire de Physique Théorique, École Normale Supérieure, CNRS, PSL University, Sorbonne Université, Paris 75005, France
- Instituut voor Theoretische Fysica, KU Leuven 3001, Belgium
| | - Christophe Mora
- Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Université, Université Paris Diderot-Sorbonne Paris Cité, Paris 75005, France
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58
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Ikonen J, Goetz J, Ilves J, Keränen A, Gunyho AM, Partanen M, Tan KY, Hazra D, Grönberg L, Vesterinen V, Simbierowicz S, Hassel J, Möttönen M. Qubit Measurement by Multichannel Driving. PHYSICAL REVIEW LETTERS 2019; 122:080503. [PMID: 30932559 DOI: 10.1103/physrevlett.122.080503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/13/2018] [Indexed: 06/09/2023]
Abstract
We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode. The separation of the bosonic states corresponding to different qubit states begins essentially immediately at maximum rate, leading to a speedup in the measurement protocol. Also the bosonic mode can be simultaneously driven to optimize measurement speed and fidelity. We experimentally test this measurement protocol using a superconducting qubit coupled to a resonator mode. For a certain measurement time, we observe that the conventional dispersive readout yields close to 100% higher average measurement error than our protocol. Finally, we use an additional resonator drive to leave the resonator state to vacuum if the qubit is in the ground state during the measurement protocol. This suggests that the proposed measurement technique may become useful in unconditionally resetting the resonator to a vacuum state after the measurement pulse.
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Affiliation(s)
- Joni Ikonen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Jan Goetz
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Jesper Ilves
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Aarne Keränen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Andras M Gunyho
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Matti Partanen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Kuan Y Tan
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Dibyendu Hazra
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Leif Grönberg
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Visa Vesterinen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Slawomir Simbierowicz
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Juha Hassel
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Mikko Möttönen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
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59
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Hu L, Wu SH, Cai W, Ma Y, Mu X, Xu Y, Wang H, Song Y, Deng DL, Zou CL, Sun L. Quantum generative adversarial learning in a superconducting quantum circuit. SCIENCE ADVANCES 2019; 5:eaav2761. [PMID: 30746476 PMCID: PMC6357722 DOI: 10.1126/sciadv.aav2761] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/11/2018] [Indexed: 05/25/2023]
Abstract
Generative adversarial learning is one of the most exciting recent breakthroughs in machine learning. It has shown splendid performance in a variety of challenging tasks such as image and video generation. More recently, a quantum version of generative adversarial learning has been theoretically proposed and shown to have the potential of exhibiting an exponential advantage over its classical counterpart. Here, we report the first proof-of-principle experimental demonstration of quantum generative adversarial learning in a superconducting quantum circuit. We demonstrate that, after several rounds of adversarial learning, a quantum-state generator can be trained to replicate the statistics of the quantum data output from a quantum channel simulator, with a high fidelity (98.8% on average) so that the discriminator cannot distinguish between the true and the generated data. Our results pave the way for experimentally exploring the intriguing long-sought-after quantum advantages in machine learning tasks with noisy intermediate-scale quantum devices.
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Affiliation(s)
- Ling Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Shu-Hao Wu
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Weizhou Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuwei Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Xianghao Mu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Haiyan Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yipu Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Dong-Ling Deng
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Chang-Ling Zou
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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60
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Experimental repetitive quantum channel simulation. Sci Bull (Beijing) 2018; 63:1551-1557. [PMID: 36751075 DOI: 10.1016/j.scib.2018.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/17/2018] [Accepted: 11/19/2018] [Indexed: 11/22/2022]
Abstract
Universal control of quantum systems is a major goal to be achieved for quantum information processing, which demands thorough understanding of fundamental quantum mechanics and promises applications of quantum technologies. So far, most studies concentrate on ideally isolated quantum systems governed by unitary evolutions, while practical quantum systems are open and described by quantum channels due to their inevitable coupling to environment. Here, we experimentally simulate arbitrary quantum channels for an open quantum system, i.e. a single photonic qubit in a superconducting quantum circuit. The arbitrary channel simulation is achieved with minimum resource of only one ancilla qubit and measurement-based adaptive control. By repetitively implementing the quantum channel simulation, we realize an arbitrary Liouvillian for a continuous evolution of an open quantum system for the first time. Our experiment provides not only a testbed for understanding quantum noise and decoherence, but also a powerful tool for full control of practical open quantum systems.
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61
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Quantum-enhanced sensing using non-classical spin states of a highly magnetic atom. Nat Commun 2018; 9:4955. [PMID: 30470745 PMCID: PMC6251866 DOI: 10.1038/s41467-018-07433-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/26/2018] [Indexed: 11/08/2022] Open
Abstract
Coherent superposition states of a mesoscopic quantum object play a major role in our understanding of the quantum to classical boundary, as well as in quantum-enhanced metrology and computing. However, their practical realization and manipulation remains challenging, requiring a high degree of control of the system and its coupling to the environment. Here, we use dysprosium atoms-the most magnetic element in its ground state-to realize coherent superpositions between electronic spin states of opposite orientation, with a mesoscopic spin size J = 8. We drive coherent spin states to quantum superpositions using non-linear light-spin interactions, observing a series of collapses and revivals of quantum coherence. These states feature highly non-classical behavior, with a sensitivity to magnetic fields enhanced by a factor 13.9(1.1) compared to coherent spin states-close to the Heisenberg limit 2J = 16-and an intrinsic fragility to environmental noise.
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62
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Quantum control of surface acoustic-wave phonons. Nature 2018; 563:661-665. [DOI: 10.1038/s41586-018-0719-5] [Citation(s) in RCA: 184] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 09/10/2018] [Indexed: 11/08/2022]
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63
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Viennot JJ, Ma X, Lehnert KW. Phonon-Number-Sensitive Electromechanics. PHYSICAL REVIEW LETTERS 2018; 121:183601. [PMID: 30444407 DOI: 10.1103/physrevlett.121.183601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Indexed: 06/09/2023]
Abstract
We use the strong intrinsic nonlinearity of a microwave superconducting qubit with a 4 GHz transition frequency to directly detect and control the energy of a micromechanical oscillator vibrating at 25 MHz. The qubit and the oscillator are coupled electrostatically at a rate of approximately 2π×22 MHz. In this far off-resonant regime, the qubit frequency is shifted by 0.52 MHz per oscillator phonon, or about 14% of the 3.7 MHz qubit linewidth. The qubit behaves as a vibrational energy detector and from its line shape we extract the phonon number distribution of the oscillator. We manipulate this distribution by driving number state sensitive sideband transitions and creating profoundly nonthermal states. Finally, by driving the lower frequency sideband transition, we cool the oscillator and increase its ground state population up to 0.48±0.13, close to a factor of 8 above its value at thermal equilibrium. These results demonstrate a new class of electromechanics experiments that are a promising strategy for quantum nondemolition measurements and nonclassical state preparation.
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Affiliation(s)
- J J Viennot
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - X Ma
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - K W Lehnert
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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64
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Dynamics of probing a quantum-dot spin qubit with superconducting resonator photons. Sci Rep 2018; 8:15761. [PMID: 30361643 PMCID: PMC6202405 DOI: 10.1038/s41598-018-34108-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/10/2018] [Indexed: 11/30/2022] Open
Abstract
The hybrid system of electron spins and resonator photons is an attractive architecture for quantum computing owing to the long coherence times of spins and the promise of long-distance coupling between arbitrary pairs of qubits via photons. For the device to serve as a building block for a quantum processer, it is also necessary to readout the spin qubit state. Here we analyze in detail the measurement process of an electron spin singlet-triplet qubit in quantum dots using a coupled superconducting resonator. We show that the states of the spin singlet-triplet qubit lead to readily observable features in the spectrum of a microwave field through the resonator. These features provide useful information on the hybrid system. Moreover, we discuss the working points which can be implemented with high performance in the current state-of-the-art devices. These results can be used to construct the high fidelity measurement toolbox in the spin-circuit QED system.
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65
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Davis EJ, Wang Z, Safavi-Naeini AH, Schleier-Smith MH. Painting Nonclassical States of Spin or Motion with Shaped Single Photons. PHYSICAL REVIEW LETTERS 2018; 121:123602. [PMID: 30296158 DOI: 10.1103/physrevlett.121.123602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Indexed: 06/08/2023]
Abstract
We propose a robust scheme for generating macroscopic superposition states of spin or motion with the aid of a single photon. Shaping the wave packet of the photon enables high-fidelity preparation of nonclassical states of matter even in the presence of photon loss. Success is heralded by photodetection, enabling the scheme to be implemented with a weak coherent field. We analyze applications to preparing Schrödinger cat states of a collective atomic spin or of a mechanical oscillator coupled to an optical resonator. The method generalizes to preparing arbitrary superpositions of coherent states, enabling full quantum control. We illustrate this versatility by showing how to prepare Dicke or Fock states, as well as superpositions in the Dicke or Fock basis.
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Affiliation(s)
- Emily J Davis
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Zhaoyou Wang
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Amir H Safavi-Naeini
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
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66
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Rosenblum S, Reinhold P, Mirrahimi M, Jiang L, Frunzio L, Schoelkopf RJ. Fault-tolerant detection of a quantum error. Science 2018; 361:266-270. [PMID: 30026224 DOI: 10.1126/science.aat3996] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/22/2018] [Indexed: 11/02/2022]
Abstract
A critical component of any quantum error-correcting scheme is detection of errors by using an ancilla system. However, errors occurring in the ancilla can propagate onto the logical qubit, irreversibly corrupting the encoded information. We demonstrate a fault-tolerant error-detection scheme that suppresses spreading of ancilla errors by a factor of 5, while maintaining the assignment fidelity. The same method is used to prevent propagation of ancilla excitations, increasing the logical qubit dephasing time by an order of magnitude. Our approach is hardware-efficient, as it uses a single multilevel transmon ancilla and a cavity-encoded logical qubit, whose interaction is engineered in situ by using an off-resonant sideband drive. The results demonstrate that hardware-efficient approaches that exploit system-specific error models can yield advances toward fault-tolerant quantum computation.
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Affiliation(s)
- S Rosenblum
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA. .,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - P Reinhold
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - M Mirrahimi
- Yale Quantum Institute, Yale University, New Haven, CT 06520, USA.,QUANTIC team, INRIA de Paris, 2 Rue Simone Iff, 75012 Paris, France
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - L Frunzio
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - R J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
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67
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Xu Y, Cai W, Ma Y, Mu X, Hu L, Chen T, Wang H, Song YP, Xue ZY, Yin ZQ, Sun L. Single-Loop Realization of Arbitrary Nonadiabatic Holonomic Single-Qubit Quantum Gates in a Superconducting Circuit. PHYSICAL REVIEW LETTERS 2018; 121:110501. [PMID: 30265093 DOI: 10.1103/physrevlett.121.110501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Indexed: 06/08/2023]
Abstract
Geometric phases are noise resilient, and thus provide a robust way towards high-fidelity quantum manipulation. Here we experimentally demonstrate arbitrary nonadiabatic holonomic single-qubit quantum gates for both a superconducting transmon qubit and a microwave cavity in a single-loop way. In both cases, an auxiliary state is utilized, and two resonant microwave drives are simultaneously applied with well-controlled but varying amplitudes and phases for the arbitrariness of the gate. The resulting gates on the transmon qubit achieve a fidelity of 0.996 characterized by randomized benchmarking and the ones on the cavity show an averaged fidelity of 0.978 based on a full quantum process tomography. In principle, a nontrivial two-qubit holonomic gate between the qubit and the cavity can also be realized based on our presented experimental scheme. Our experiment thus paves the way towards practical nonadiabatic holonomic quantum manipulation with both qubits and cavities in a superconducting circuit.
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Affiliation(s)
- Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Mu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Tao Chen
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zheng-Yuan Xue
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - Zhang-Qi Yin
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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68
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Chou KS, Blumoff JZ, Wang CS, Reinhold PC, Axline CJ, Gao YY, Frunzio L, Devoret MH, Jiang L, Schoelkopf RJ. Deterministic teleportation of a quantum gate between two logical qubits. Nature 2018; 561:368-373. [PMID: 30185908 DOI: 10.1038/s41586-018-0470-y] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 06/27/2018] [Indexed: 11/09/2022]
Abstract
A quantum computer has the potential to efficiently solve problems that are intractable for classical computers. However, constructing a large-scale quantum processor is challenging because of the errors and noise that are inherent in real-world quantum systems. One approach to addressing this challenge is to utilize modularity-a strategy used frequently in nature and engineering to build complex systems robustly. Such an approach manages complexity and uncertainty by assembling small, specialized components into a larger architecture. These considerations have motivated the development of a quantum modular architecture, in which separate quantum systems are connected into a quantum network via communication channels1,2. In this architecture, an essential tool for universal quantum computation is the teleportation of an entangling quantum gate3-5, but such teleportation has hitherto not been realized as a deterministic operation. Here we experimentally demonstrate the teleportation of a controlled-NOT (CNOT) gate, which we make deterministic by using real-time adaptive control. In addition, we take a crucial step towards implementing robust, error-correctable modules by enacting the gate between two logical qubits, encoding quantum information redundantly in the states of superconducting cavities6. By using such an error-correctable encoding, our teleported gate achieves a process fidelity of 79 per cent. Teleported gates have implications for fault-tolerant quantum computation3, and when realized within a network can have broad applications in quantum communication, metrology and simulations1,2,7. Our results illustrate a compelling approach for implementing multi-qubit operations on logical qubits and, if integrated with quantum error-correction protocols, indicate a promising path towards fault-tolerant quantum computation using a modular architecture.
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Affiliation(s)
- Kevin S Chou
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA. .,Yale Quantum Institute, Yale University, New Haven, CT, USA.
| | - Jacob Z Blumoff
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA.,HRL Laboratories, Malibu, CA, USA
| | - Christopher S Wang
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - Philip C Reinhold
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - Christopher J Axline
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - Yvonne Y Gao
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - L Frunzio
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - M H Devoret
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - Liang Jiang
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - R J Schoelkopf
- Department of Applied Physics and Physics, Yale University, New Haven, CT, USA. .,Yale Quantum Institute, Yale University, New Haven, CT, USA.
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69
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Maleki Y, Zheltikov AM. Witnessing quantum entanglement in ensembles of nitrogen-vacancy centers coupled to a superconducting resonator. OPTICS EXPRESS 2018; 26:17849-17858. [PMID: 30114070 DOI: 10.1364/oe.26.017849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/28/2018] [Indexed: 06/08/2023]
Abstract
A hybrid quantum device consisting of three ensembles of nitrogen-vacancy centers (NVEs) whose spins are collectively coupled to a superconducting coplanar waveguide resonator is shown to enable the generation of controllable tripartite macroscopic entangled states. The density matrix of such NVEs can be encoded to recast a three-qubit system state, which can be characterized in terms of the entanglement witnesses in relation to the Greenberger-Horne-Zeilinger (GHZ) states. We identify the parameter space within which the generated entangled states can have an arbitrarily large overlap with GHZ states, indicating an enhanced entanglement in the system.
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70
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Eichler C, Petta JR. Realizing a Circuit Analog of an Optomechanical System with Longitudinally Coupled Superconducting Resonators. PHYSICAL REVIEW LETTERS 2018; 120:227702. [PMID: 29906158 DOI: 10.1103/physrevlett.120.227702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Indexed: 06/08/2023]
Abstract
We realize a superconducting circuit analog of the generic cavity-optomechanical Hamiltonian by longitudinally coupling two superconducting resonators, which are an order of magnitude different in frequency. We achieve longitudinal coupling by embedding a superconducting quantum interference device into a high frequency resonator, making its resonance frequency depend on the zero point current fluctuations of a nearby low frequency LC resonator. By applying sideband drive fields we enhance the intrinsic coupling strength of about 15 kHz up to 280 kHz by controlling the amplitude of the drive field. Our results pave the way towards the exploration of optomechanical effects in a fully superconducting platform and could enable quantum optics experiments with photons in the yet unexplored radio frequency band.
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Affiliation(s)
- C Eichler
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - J R Petta
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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71
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Leroux C, Govia LCG, Clerk AA. Enhancing Cavity Quantum Electrodynamics via Antisqueezing: Synthetic Ultrastrong Coupling. PHYSICAL REVIEW LETTERS 2018; 120:093602. [PMID: 29547301 DOI: 10.1103/physrevlett.120.093602] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/01/2017] [Indexed: 06/08/2023]
Abstract
We present and analyze a method where parametric (two-photon) driving of a cavity is used to exponentially enhance the light-matter coupling in a generic cavity QED setup, with time-dependent control. Our method allows one to enhance weak-coupling systems, such that they enter the strong coupling regime (where the coupling exceeds dissipative rates) and even the ultrastrong coupling regime (where the coupling is comparable to the cavity frequency). As an example, we show how the scheme allows one to use a weak-coupling system to adiabatically prepare the highly entangled ground state of the ultrastrong coupling system. The resulting state could be used for remote entanglement applications.
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Affiliation(s)
- C Leroux
- Department of Physics, McGill University, 3600 rue University, Montréal, Québec, Canada H3A 2T8
| | - L C G Govia
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA
| | - A A Clerk
- Institute for Molecular Engineering, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA
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72
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Landon-Cardinal O, Govia LCG, Clerk AA. Quantitative Tomography for Continuous Variable Quantum Systems. PHYSICAL REVIEW LETTERS 2018; 120:090501. [PMID: 29547319 DOI: 10.1103/physrevlett.120.090501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Indexed: 06/08/2023]
Abstract
We present a continuous variable tomography scheme that reconstructs the Husimi Q function (Wigner function) by Lagrange interpolation, using measurements of the Q function (Wigner function) at the Padua points, conjectured to be optimal sampling points for two dimensional reconstruction. Our approach drastically reduces the number of measurements required compared to using equidistant points on a regular grid, although reanalysis of such experiments is possible. The reconstruction algorithm produces a reconstructed function with exponentially decreasing error and quasilinear runtime in the number of Padua points. Moreover, using the interpolating polynomial of the Q function, we present a technique to directly estimate the density matrix elements of the continuous variable state, with only a linear propagation of input measurement error. Furthermore, we derive a state-independent analytical bound on this error, such that our estimate of the density matrix is accompanied by a measure of its uncertainty.
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Affiliation(s)
- Olivier Landon-Cardinal
- Department of Physics, McGill University, 3600 rue University, Montréal, Québec, Canada H3A 2T8
| | - Luke C G Govia
- Department of Physics, McGill University, 3600 rue University, Montréal, Québec, Canada H3A 2T8
- Institute for Molecular Engineering, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637, USA
| | - Aashish A Clerk
- Department of Physics, McGill University, 3600 rue University, Montréal, Québec, Canada H3A 2T8
- Institute for Molecular Engineering, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637, USA
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73
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Liu T, Guo BQ, Yu CS, Zhang WN. One-step implementation of a hybrid Fredkin gate with quantum memories and single superconducting qubit in circuit QED and its applications. OPTICS EXPRESS 2018; 26:4498-4511. [PMID: 29475300 DOI: 10.1364/oe.26.004498] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/04/2018] [Indexed: 06/08/2023]
Abstract
In a recent remarkable experiment [Sci. Adv. 2, e1501531 (2016)], a 3-qubit quantum Fredkin (i.e., controlled-SWAP) gate was demonstrated by using linear optics. Here we propose a simple experimental scheme by utilizing the dispersive interaction in superconducting quantum circuit to implement a hybrid Fredkin gate with a superconducting flux qubit as the control qubit and two separated quantum memories as the target qudits. The quantum memories considered here are prepared by the superconducting coplanar waveguide resonators or nitrogen-vacancy center ensembles. In particular, it is shown that this Fredkin gate can be realized using a single-step operation and more importantly, each target qudit can be in an arbitrary state with arbitrary degrees of freedom. Furthermore, we show that this experimental scheme has many potential applications in quantum computation and quantum information processing such as generating arbitrary entangled states (discrete-variable states or continuous-variable states) of the two memories, measuring the fidelity and the entanglement between the two memories. With state-of-the-art circuit QED technology, the numerical simulation is performed to demonstrate that two-memory NOON states, entangled coherent states, and entangled cat states can be efficiently synthesized.
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74
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A CNOT gate between multiphoton qubits encoded in two cavities. Nat Commun 2018; 9:652. [PMID: 29440766 PMCID: PMC5811561 DOI: 10.1038/s41467-018-03059-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 01/16/2018] [Indexed: 11/08/2022] Open
Abstract
Entangling gates between qubits are a crucial component for performing algorithms in quantum computers. However, any quantum algorithm must ultimately operate on error-protected logical qubits encoded in high-dimensional systems. Typically, logical qubits are encoded in multiple two-level systems, but entangling gates operating on such qubits are highly complex and have not yet been demonstrated. Here we realize a controlled NOT (CNOT) gate between two multiphoton qubits in two microwave cavities. In this approach, we encode a qubit in the high-dimensional space of a single cavity mode, rather than in multiple two-level systems. We couple two such encoded qubits together through a transmon, which is driven by an RF pump to apply the gate within 190 ns. This is two orders of magnitude shorter than the decoherence time of the transmon, enabling a high-fidelity gate operation. These results are an important step towards universal algorithms on error-corrected logical qubits.
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75
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Bohmann M, Tiedau J, Bartley T, Sperling J, Silberhorn C, Vogel W. Incomplete Detection of Nonclassical Phase-Space Distributions. PHYSICAL REVIEW LETTERS 2018; 120:063607. [PMID: 29481264 DOI: 10.1103/physrevlett.120.063607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 06/08/2023]
Abstract
We implement the direct sampling of negative phase-space functions via unbalanced homodyne measurement using click-counting detectors. The negativities significantly certify nonclassical light in the high-loss regime using a small number of detectors which cannot resolve individual photons. We apply our method to heralded single-photon states and experimentally demonstrate the most significant certification of nonclassicality for only two detection bins. By contrast, the frequently applied Wigner function fails to directly indicate such quantum characteristics for the quantum efficiencies present in our setup without applying additional reconstruction algorithms. Therefore, we realize a robust and reliable approach to characterize nonclassical light in phase space under realistic conditions.
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Affiliation(s)
- M Bohmann
- Arbeitsgruppe Theoretische Quantenoptik, Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
| | - J Tiedau
- Integrated Quantum Optics Group, Applied Physics, University of Paderborn, 33098 Paderborn, Germany
| | - T Bartley
- Integrated Quantum Optics Group, Applied Physics, University of Paderborn, 33098 Paderborn, Germany
| | - J Sperling
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - C Silberhorn
- Integrated Quantum Optics Group, Applied Physics, University of Paderborn, 33098 Paderborn, Germany
| | - W Vogel
- Arbeitsgruppe Theoretische Quantenoptik, Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
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76
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Abdi M, Hwang MJ, Aghtar M, Plenio MB. Spin-Mechanical Scheme with Color Centers in Hexagonal Boron Nitride Membranes. PHYSICAL REVIEW LETTERS 2017; 119:233602. [PMID: 29286681 DOI: 10.1103/physrevlett.119.233602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Indexed: 06/07/2023]
Abstract
Recently observed quantum emitters in hexagonal boron nitride (hBN) membranes have a potential for achieving high accessibility and controllability thanks to the lower spatial dimension. Moreover, these objects naturally have a high sensitivity to vibrations of the hosting membrane due to its low mass density and high elasticity modulus. Here, we propose and analyze a spin-mechanical system based on color centers in a suspended hBN mechanical resonator. Through group theoretical analyses and ab initio calculation of the electronic and spin properties of such a system, we identify a spin doublet ground state and demonstrate that a spin-motion interaction can be engineered, which enables ground-state cooling of the mechanical resonator. We also present a toolbox for initialization, rotation, and readout of the defect spin qubit. As a result, the proposed setup presents the possibility for studying a wide range of physics. To illustrate its assets, we show that a fast and noise-resilient preparation of a multicomponent cat state and a squeezed state of the mechanical resonator is possible; the latter is achieved by realizing the extremely detuned, ultrastrong coupling regime of the Rabi model, where a phonon superradiant phase transition is expected to occur.
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Affiliation(s)
- Mehdi Abdi
- Institut für Theoretische Physik und IQST, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany
| | - Myung-Joong Hwang
- Institut für Theoretische Physik und IQST, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany
| | - Mortaza Aghtar
- Institut für Theoretische Physik und IQST, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany
| | - Martin B Plenio
- Institut für Theoretische Physik und IQST, Albert-Einstein-Allee 11, Universität Ulm, 89069 Ulm, Germany
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77
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Experimentally simulating the dynamics of quantum light and matter at deep-strong coupling. Nat Commun 2017; 8:1715. [PMID: 29167425 PMCID: PMC5700074 DOI: 10.1038/s41467-017-01061-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 08/15/2017] [Indexed: 11/08/2022] Open
Abstract
The quantum Rabi model describing the fundamental interaction between light and matter is a cornerstone of quantum physics. It predicts exotic phenomena like quantum phase transitions and ground-state entanglement in ultrastrong and deep-strong coupling regimes, where coupling strengths are comparable to or larger than subsystem energies. Demonstrating dynamics remains an outstanding challenge, the few experiments reaching these regimes being limited to spectroscopy. Here, we employ a circuit quantum electrodynamics chip with moderate coupling between a resonator and transmon qubit to realise accurate digital quantum simulation of deep-strong coupling dynamics. We advance the state of the art in solid-state digital quantum simulation by using up to 90 second-order Trotter steps and probing both subsystems in a combined Hilbert space dimension of ∼80, demonstrating characteristic Schrödinger-cat-like entanglement and large photon build-up. Our approach will enable exploration of extreme coupling regimes and quantum phase transitions, and demonstrates a clear first step towards larger complexities such as in the Dicke model.
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78
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Rab AS, Polino E, Man ZX, Ba An N, Xia YJ, Spagnolo N, Lo Franco R, Sciarrino F. Entanglement of photons in their dual wave-particle nature. Nat Commun 2017; 8:915. [PMID: 29030635 PMCID: PMC5688178 DOI: 10.1038/s41467-017-01058-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 08/13/2017] [Indexed: 11/09/2022] Open
Abstract
Wave-particle duality is the most fundamental description of the nature of a quantum object, which behaves like a classical particle or wave depending on the measurement apparatus. On the other hand, entanglement represents nonclassical correlations of composite quantum systems, being also a key resource in quantum information. Despite the very recent observations of wave-particle superposition and entanglement, whether these two fundamental traits of quantum mechanics can emerge simultaneously remains an open issue. Here we introduce and experimentally realize a scheme that deterministically generates entanglement between the wave and particle states of two photons. The elementary tool allowing this achievement is a scalable single-photon setup which can be in principle extended to generate multiphoton wave-particle entanglement. Our study reveals that photons can be entangled in their dual wave-particle behavior and opens the way to potential applications in quantum information protocols exploiting the wave-particle degrees of freedom to encode qubits. Here the authors experimentally realize a scheme that deterministically generates entanglement between the wave and particle states of two photons using a scalable all-optical scheme. They achieve this result by first showing generation of controllable single-photon wave-particle superposition states.
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Affiliation(s)
- Adil S Rab
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro, 5, Roma, I-00185, Italy
| | - Emanuele Polino
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro, 5, Roma, I-00185, Italy
| | - Zhong-Xiao Man
- Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu, 273165, China.
| | - Nguyen Ba An
- Center for Theoretical Physics, Institute of Physics, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, 10000, Hanoi, Vietnam
| | - Yun-Jie Xia
- Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu, 273165, China
| | - Nicolò Spagnolo
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro, 5, Roma, I-00185, Italy
| | - Rosario Lo Franco
- Dipartimento di Energia, Ingegneria dell'Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, Edificio 9, Palermo, 90128, Italy. .,Dipartimento di Fisica e Chimica, Università di Palermo, via Archirafi 36, Palermo, 90123, Italy.
| | - Fabio Sciarrino
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro, 5, Roma, I-00185, Italy.
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79
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Analog quantum simulation of the Rabi model in the ultra-strong coupling regime. Nat Commun 2017; 8:779. [PMID: 28974675 PMCID: PMC5626763 DOI: 10.1038/s41467-017-00894-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 08/03/2017] [Indexed: 11/20/2022] Open
Abstract
The quantum Rabi model describes the fundamental mechanism of light-matter interaction. It consists of a two-level atom or qubit coupled to a quantized harmonic mode via a transversal interaction. In the weak coupling regime, it reduces to the well-known Jaynes–Cummings model by applying a rotating wave approximation. The rotating wave approximation breaks down in the ultra-strong coupling regime, where the effective coupling strength g is comparable to the energy ω of the bosonic mode, and remarkable features in the system dynamics are revealed. Here we demonstrate an analog quantum simulation of an effective quantum Rabi model in the ultra-strong coupling regime, achieving a relative coupling ratio of g/ω ~ 0.6. The quantum hardware of the simulator is a superconducting circuit embedded in a cQED setup. We observe fast and periodic quantum state collapses and revivals of the initial qubit state, being the most distinct signature of the synthesized model. An analog quantum simulation scheme has been explored with a quantum hardware based on a superconducting circuit. Here the authors investigate the time evolution of the quantum Rabi model at ultra-strong coupling conditions, which is synthesized by slowing down the system dynamics in an effective frame.
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80
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Johnson KG, Wong-Campos JD, Neyenhuis B, Mizrahi J, Monroe C. Ultrafast creation of large Schrödinger cat states of an atom. Nat Commun 2017; 8:697. [PMID: 28951588 PMCID: PMC5614983 DOI: 10.1038/s41467-017-00682-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 07/20/2017] [Indexed: 11/23/2022] Open
Abstract
Mesoscopic quantum superpositions, or Schrödinger cat states, are widely studied for fundamental investigations of quantum measurement and decoherence as well as applications in sensing and quantum information science. The generation and maintenance of such states relies upon a balance between efficient external coherent control of the system and sufficient isolation from the environment. Here we create a variety of cat states of a single trapped atom’s motion in a harmonic oscillator using ultrafast laser pulses. These pulses produce high fidelity impulsive forces that separate the atom into widely separated positions, without restrictions that typically limit the speed of the interaction or the size and complexity of the resulting motional superposition. This allows us to quickly generate and measure cat states larger than previously achieved in a harmonic oscillator, and create complex multi-component superposition states in atoms. Generation of mesoscopic quantum superpositions requires both reliable coherent control and isolation from the environment. Here, the authors succeed in creating a variety of cat states of a single trapped atom, mapping spin superpositions into spatial superpositions using ultrafast laser pulses.
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Affiliation(s)
- K G Johnson
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA.
| | - J D Wong-Campos
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - B Neyenhuis
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - J Mizrahi
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - C Monroe
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
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81
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Liu YY, Stehlik J, Eichler C, Mi X, Hartke TR, Gullans MJ, Taylor JM, Petta JR. Threshold Dynamics of a Semiconductor Single Atom Maser. PHYSICAL REVIEW LETTERS 2017; 119:097702. [PMID: 28949587 DOI: 10.1103/physrevlett.119.097702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate a single atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high-quality-factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and masing. We develop a dynamic tuning protocol that allows us to controllably increase the time-averaged repumping rate of the DQD at a fixed level detuning, and quantitatively study the transition through the masing threshold. We further examine the crossover from incoherent to coherent emission by measuring the photon statistics across the masing transition. The observed threshold behavior is in agreement with an existing single atom maser theory when small corrections from lead emission are taken into account.
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Affiliation(s)
- Y-Y Liu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - J Stehlik
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - C Eichler
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - X Mi
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - T R Hartke
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - M J Gullans
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, NIST and University of Maryland, College Park, Maryland 20742, USA
| | - J M Taylor
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, NIST and University of Maryland, College Park, Maryland 20742, USA
| | - J R Petta
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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82
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Cohen J, Smith WC, Devoret MH, Mirrahimi M. Degeneracy-Preserving Quantum Nondemolition Measurement of Parity-Type Observables for Cat Qubits. PHYSICAL REVIEW LETTERS 2017; 119:060503. [PMID: 28949639 DOI: 10.1103/physrevlett.119.060503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 06/07/2023]
Abstract
A central requirement for any quantum error correction scheme is the ability to perform quantum nondemolition measurements of an error syndrome, corresponding to a special symmetry property of the encoding scheme. It is in particular important that such a measurement does not introduce extra error mechanisms, not included in the error model of the correction scheme. In this Letter, we ensure such a robustness by designing an interaction with a measurement device that preserves the degeneracy of the measured observable. More precisely, we propose a scheme to perform continuous and quantum nondemolition measurement of photon-number parity in a microwave cavity. This corresponds to the error syndrome in a class of error correcting codes called the cat codes, which have recently proven to be efficient and versatile for quantum information processing. In our design, we exploit the strongly nonlinear Hamiltonian of a high-impedance Josephson circuit, coupling a high-Q cavity storage cavity mode to a low-Q readout one. By driving the readout resonator at its resonance, the phase of the reflected or transmitted signal carries directly exploitable information on parity-type observables for encoded cat qubits of the high-Q mode.
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Affiliation(s)
- Joachim Cohen
- QUANTIC project-team, INRIA Paris, 75012 Paris, France
| | - W Clarke Smith
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Michel H Devoret
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Mazyar Mirrahimi
- QUANTIC project-team, INRIA Paris, 75012 Paris, France
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
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83
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Implementing a universal gate set on a logical qubit encoded in an oscillator. Nat Commun 2017; 8:94. [PMID: 28733580 PMCID: PMC5522494 DOI: 10.1038/s41467-017-00045-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 04/27/2017] [Indexed: 11/09/2022] Open
Abstract
A logical qubit is a two-dimensional subspace of a higher dimensional system, chosen such that it is possible to detect and correct the occurrence of certain errors. Manipulation of the encoded information generally requires arbitrary and precise control over the entire system. Whether based on multiple physical qubits or larger dimensional modes such as oscillators, the individual elements in realistic devices will always have residual interactions, which must be accounted for when designing logical operations. Here we demonstrate a holistic control strategy which exploits accurate knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system. We use this approach to realize high-fidelity (98.5%, inferred), decoherence-limited operations on a logical qubit encoded in a superconducting cavity resonator using four-component cat states. Our results show the power of applying numerical techniques to control linear oscillators and pave the way for utilizing their large Hilbert space as a resource in quantum information processing.A logical qubit is a two-dimensional subspace of a higher dimensional system, whose manipulation requires precise control over the whole system. Here the authors demonstrate a control strategy which exploits precise knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system.
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84
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Kono S, Masuyama Y, Ishikawa T, Tabuchi Y, Yamazaki R, Usami K, Koshino K, Nakamura Y. Nonclassical Photon Number Distribution in a Superconducting Cavity under a Squeezed Drive. PHYSICAL REVIEW LETTERS 2017; 119:023602. [PMID: 28753365 DOI: 10.1103/physrevlett.119.023602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
A superconducting qubit in the strong dispersive regime of circuit quantum electrodynamics is a powerful probe for microwave photons in a cavity mode. In this regime, a qubit excitation spectrum is split into multiple peaks, with each peak corresponding to an individual photon number in the cavity (discrete ac Stark shift). Here, we measure the qubit spectrum in a cavity that is driven continuously with a squeezed vacuum generated by a Josephson parametric amplifier. By fitting the obtained spectrum with a model which takes into account the finite qubit excitation power, we determine the photon number distribution, which reveals an even-odd photon number oscillation and quantitatively fulfills Klyshko's criterion for nonclassicality.
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Affiliation(s)
- S Kono
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Y Masuyama
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - T Ishikawa
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Y Tabuchi
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - R Yamazaki
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - K Usami
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - K Koshino
- College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827, Japan
| | - Y Nakamura
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
- Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198, Japan
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85
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Lachance-Quirion D, Tabuchi Y, Ishino S, Noguchi A, Ishikawa T, Yamazaki R, Nakamura Y. Resolving quanta of collective spin excitations in a millimeter-sized ferromagnet. SCIENCE ADVANCES 2017; 3:e1603150. [PMID: 28695204 PMCID: PMC5498106 DOI: 10.1126/sciadv.1603150] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/18/2017] [Indexed: 05/24/2023]
Abstract
Combining different physical systems in hybrid quantum circuits opens up novel possibilities for quantum technologies. In quantum magnonics, quanta of collective excitation modes in a ferromagnet, called magnons, interact coherently with qubits to access quantum phenomena of magnonics. We use this architecture to probe the quanta of collective spin excitations in a millimeter-sized ferromagnetic crystal. More specifically, we resolve magnon number states through spectroscopic measurements of a superconducting qubit with the hybrid system in the strong dispersive regime. This enables us to detect a change in the magnetic moment of the ferromagnet equivalent to a single spin flipped among more than 1019 spins. Our demonstration highlights the strength of hybrid quantum systems to provide powerful tools for quantum sensing and quantum information processing.
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Affiliation(s)
- Dany Lachance-Quirion
- Institut quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Yutaka Tabuchi
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Seiichiro Ishino
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Atsushi Noguchi
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Toyofumi Ishikawa
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Rekishu Yamazaki
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Yasunobu Nakamura
- Research Center for Advanced Science and Technology, University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
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86
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Zapletal P, Filip R. Multi-copy quantifiers for single-photon states. Sci Rep 2017; 7:1484. [PMID: 28469155 PMCID: PMC5431150 DOI: 10.1038/s41598-017-01333-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 03/29/2017] [Indexed: 11/09/2022] Open
Abstract
Single-photon states are basic resources for hybrid quantum technology with non-Gaussian states of light. Accelerating quantum technology is already able to produce high-quality single-photon states. These states can be used for hybrid quantum information processing, based on a nonclassical phase-space interference represented by negativity of a Wigner function. Therefore, new quantifiers, capable of evaluating such high-quality single-photon states, are required. We propose and analyze quantifiers which process multiple estimates of single-photon state’s statistics. The quantifiers simulate basic capability of single photons to conditionally bunch into a single mode and form a Fock state. This state exhibits complex nonclassical phase-space interference effects making its Wigner function negative in multiple areas. The quantifiers directly evaluate a presence of the multiple negativities corresponding to the Fock state. We verify applicability of the quantifiers by using them to single-photon states from recent experiments. The quantifiers can be further extended to also test indistinguishability of single-photon states. It allows to verify quantum interference of light from single-photon emitters more sensitively than in the traditional Hong-Ou-Mandel test. Besides quantum optics, the multi-copy quantifiers can be also applied to experiments with atomic memories and mechanical oscillators.
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Affiliation(s)
- Petr Zapletal
- Department of Optics, Faculty of Science, Palacký University, 17, listopadu 1192/12, 771 46, Olomouc, Czech Republic
| | - Radim Filip
- Department of Optics, Faculty of Science, Palacký University, 17, listopadu 1192/12, 771 46, Olomouc, Czech Republic.
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87
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Liu K, Xu Y, Wang W, Zheng SB, Roy T, Kundu S, Chand M, Ranadive A, Vijay R, Song Y, Duan L, Sun L. A twofold quantum delayed-choice experiment in a superconducting circuit. SCIENCE ADVANCES 2017; 3:e1603159. [PMID: 28508079 PMCID: PMC5419705 DOI: 10.1126/sciadv.1603159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/03/2017] [Indexed: 06/07/2023]
Abstract
Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.
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Affiliation(s)
- Ke Liu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Weiting Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350116, China
| | - Tanay Roy
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Suman Kundu
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Madhavi Chand
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Arpit Ranadive
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Rajamani Vijay
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Yipu Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Luming Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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88
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Ramasesh VV, Flurin E, Rudner M, Siddiqi I, Yao NY. Direct Probe of Topological Invariants Using Bloch Oscillating Quantum Walks. PHYSICAL REVIEW LETTERS 2017; 118:130501. [PMID: 28409954 DOI: 10.1103/physrevlett.118.130501] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Indexed: 05/27/2023]
Abstract
The topology of a single-particle band structure plays a fundamental role in understanding a multitude of physical phenomena. Motivated by the connection between quantum walks and such topological band structures, we demonstrate that a simple time-dependent, Bloch-oscillating quantum walk enables the direct measurement of topological invariants. We consider two classes of one-dimensional quantum walks and connect the global phase imprinted on the walker with its refocusing behavior. By disentangling the dynamical and geometric contributions to this phase, we describe a general strategy to measure the topological invariant in these quantum walks. As an example, we propose an experimental protocol in a circuit QED architecture where a superconducting transmon qubit plays the role of the coin, while the quantum walk takes place in the phase space of a cavity.
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Affiliation(s)
- V V Ramasesh
- Department of Physics, University of California, Berkeley California 94720, USA
| | - E Flurin
- Department of Physics, University of California, Berkeley California 94720, USA
| | - M Rudner
- Niels Bohr International Academy and Center for Quantum Devices, University of Copenhagen, 2100 Copenhagen, Denmark
| | - I Siddiqi
- Department of Physics, University of California, Berkeley California 94720, USA
| | - N Y Yao
- Department of Physics, University of California, Berkeley California 94720, USA
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89
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Sanz M, Las Heras U, García-Ripoll JJ, Solano E, Di Candia R. Quantum Estimation Methods for Quantum Illumination. PHYSICAL REVIEW LETTERS 2017; 118:070803. [PMID: 28256851 DOI: 10.1103/physrevlett.118.070803] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Indexed: 06/06/2023]
Abstract
Quantum illumination consists in shining quantum light on a target region immersed in a bright thermal bath with the aim of detecting the presence of a possible low-reflective object. If the signal is entangled with the receiver, then a suitable choice of the measurement offers a gain with respect to the optimal classical protocol employing coherent states. Here, we tackle this detection problem by using quantum estimation techniques to measure the reflectivity parameter of the object, showing an enhancement in the signal-to-noise ratio up to 3 dB with respect to the classical case when implementing only local measurements. Our approach employs the quantum Fisher information to provide an upper bound for the error probability, supplies the concrete estimator saturating the bound, and extends the quantum illumination protocol to non-Gaussian states. As an example, we show how Schrödinger's cat states may be used for quantum illumination.
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Affiliation(s)
- M Sanz
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain
| | - U Las Heras
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain
| | - J J García-Ripoll
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, 28006 Madrid, Spain
| | - E Solano
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48011 Bilbao, Spain
| | - R Di Candia
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195 Berlin, Germany
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90
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Hou Q, Yang W, Chen C, Yin Z. Generation of macroscopic Schrödinger cat state in diamond mechanical resonator. Sci Rep 2016; 6:37542. [PMID: 27876846 PMCID: PMC5120327 DOI: 10.1038/srep37542] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/27/2016] [Indexed: 12/03/2022] Open
Abstract
We propose a scheme to generate macroscopic Schrödinger cat state (SCS) in diamond mechanical resonator (DMR) via the dynamical strain-mediated coupling mechanism. In our model, the direct coupling between the nitrogen-vacancy (NV) center and lattice strain field enables coherent spin–phonon interactions in the quantum regime. Based on a cyclic Δ-type transition structure of the NV center constructed by combining the quantized mechanical strain field and a pair of external microwave fields, the populations of the different energy levels can be selectively transferred by controlling microwave fields, and the SCS can be created by adjusting the controllable parameters of the system. Furthermore, we demonstrate the nonclassicality of the mechanical SCS both in non-dissipative case and dissipative case. The experimental feasibility and challenge are justified using currently available technology.
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Affiliation(s)
- Qizhe Hou
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
| | - Wanli Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Changyong Chen
- Department of Physics, Shaoguan University, Shaoguan, Guangdong 512005, China
| | - Zhangqi Yin
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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91
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92
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Hoff UB, Kollath-Bönig J, Neergaard-Nielsen JS, Andersen UL. Measurement-Induced Macroscopic Superposition States in Cavity Optomechanics. PHYSICAL REVIEW LETTERS 2016; 117:143601. [PMID: 27740796 DOI: 10.1103/physrevlett.117.143601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Indexed: 06/06/2023]
Abstract
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
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Affiliation(s)
- Ulrich B Hoff
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
- Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQuS), School of Mathematics and Physics, The University of Queensland, St. Lucia QLD 4072, Australia
| | - Johann Kollath-Bönig
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
| | | | - Ulrik L Andersen
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
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93
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Quantum phase estimation using path-symmetric entangled states. Sci Rep 2016; 6:30306. [PMID: 27457267 PMCID: PMC4995609 DOI: 10.1038/srep30306] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 06/29/2016] [Indexed: 11/17/2022] Open
Abstract
We study the sensitivity of phase estimation using a generic class of path-symmetric entangled states |φ〉|0〉 + |0〉|φ〉, where an arbitrary state |φ〉 occupies one of two modes in quantum superposition. With this generalization, we identify the fundamental limit of phase estimation under energy constraint that is characterized by the photon statistics of the component state |φ〉. We show that quantum Cramer-Rao bound (QCRB) can be indefinitely lowered with super-Poissonianity of the state |φ〉. For possible measurement schemes, we demonstrate that a full photon-counting employing the path-symmetric entangled states achieves the QCRB over the entire range [0, 2π] of unknown phase shift ϕ whereas a parity measurement does so in a certain confined range of ϕ. By introducing a component state of the form , we particularly show that an arbitrarily small QCRB can be achieved even with a finite energy in an ideal situation. This component state also provides the most robust resource against photon loss among considered entangled states over the range of the average input energy Nav > 1. Finally we propose experimental schemes to generate these path-symmetric entangled states for phase estimation.
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94
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Garziano L, Macrì V, Stassi R, Di Stefano O, Nori F, Savasta S. One Photon Can Simultaneously Excite Two or More Atoms. PHYSICAL REVIEW LETTERS 2016; 117:043601. [PMID: 27494471 DOI: 10.1103/physrevlett.117.043601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Indexed: 06/06/2023]
Abstract
We consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.
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Affiliation(s)
- Luigi Garziano
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, I-98166 Messina, Italy
- CEMS, RIKEN, Saitama 351-0198, Japan
| | - Vincenzo Macrì
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, I-98166 Messina, Italy
| | - Roberto Stassi
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, I-98166 Messina, Italy
- CEMS, RIKEN, Saitama 351-0198, Japan
| | - Omar Di Stefano
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, I-98166 Messina, Italy
| | - Franco Nori
- CEMS, RIKEN, Saitama 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - Salvatore Savasta
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, I-98166 Messina, Italy
- CEMS, RIKEN, Saitama 351-0198, Japan
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95
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Chapman RJ, Ferrie C, Peruzzo A. Experimental Demonstration of Self-Guided Quantum Tomography. PHYSICAL REVIEW LETTERS 2016; 117:040402. [PMID: 27494462 DOI: 10.1103/physrevlett.117.040402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Indexed: 06/06/2023]
Abstract
Traditional methods of quantum state characterization are impractical for systems of more than a few qubits due to exponentially expensive postprocessing and data storage and lack robustness against errors and noise. Here, we experimentally demonstrate self-guided quantum tomography performed on polarization photonic qubits. The quantum state is iteratively learned by optimizing a projection measurement without any data storage or postprocessing. We experimentally demonstrate robustness against statistical noise and measurement errors on single-qubit and entangled two-qubit states.
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Affiliation(s)
- Robert J Chapman
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia and School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Christopher Ferrie
- Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Alberto Peruzzo
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia and School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
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96
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Ofek N, Petrenko A, Heeres R, Reinhold P, Leghtas Z, Vlastakis B, Liu Y, Frunzio L, Girvin SM, Jiang L, Mirrahimi M, Devoret MH, Schoelkopf RJ. Extending the lifetime of a quantum bit with error correction in superconducting circuits. Nature 2016; 536:441-5. [DOI: 10.1038/nature18949] [Citation(s) in RCA: 469] [Impact Index Per Article: 58.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/08/2016] [Indexed: 12/18/2022]
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97
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Fedorov KG, Zhong L, Pogorzalek S, Eder P, Fischer M, Goetz J, Xie E, Wulschner F, Inomata K, Yamamoto T, Nakamura Y, Di Candia R, Las Heras U, Sanz M, Solano E, Menzel EP, Deppe F, Marx A, Gross R. Displacement of Propagating Squeezed Microwave States. PHYSICAL REVIEW LETTERS 2016; 117:020502. [PMID: 27447495 DOI: 10.1103/physrevlett.117.020502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Indexed: 06/06/2023]
Abstract
Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.
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Affiliation(s)
- Kirill G Fedorov
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
| | - L Zhong
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
| | - S Pogorzalek
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - P Eder
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
| | - M Fischer
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - J Goetz
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - E Xie
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
| | - F Wulschner
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
| | - K Inomata
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - T Yamamoto
- NEC IoT Device Research Laboratories, Tsukuba, Ibaraki 305-8501, Japan
| | - Y Nakamura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - R Di Candia
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - U Las Heras
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - M Sanz
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, E-48080 Bilbao, Spain
| | - E Solano
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- 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, 48013 Bilbao, Spain
| | - E P Menzel
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
| | - F Deppe
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
| | - A Marx
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
| | - R Gross
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Nanosystems Initiative Munich (NIM), Schellingstraße 4, 80799 München, Germany
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98
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Yuan X, Liu K, Xu Y, Wang W, Ma Y, Zhang F, Yan Z, Vijay R, Sun L, Ma X. Experimental Quantum Randomness Processing Using Superconducting Qubits. PHYSICAL REVIEW LETTERS 2016; 117:010502. [PMID: 27419550 DOI: 10.1103/physrevlett.117.010502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Indexed: 06/06/2023]
Abstract
Coherently manipulating multipartite quantum correlations leads to remarkable advantages in quantum information processing. A fundamental question is whether such quantum advantages persist only by exploiting multipartite correlations, such as entanglement. Recently, Dale, Jennings, and Rudolph negated the question by showing that a randomness processing, quantum Bernoulli factory, using quantum coherence, is strictly more powerful than the one with classical mechanics. In this Letter, focusing on the same scenario, we propose a theoretical protocol that is classically impossible but can be implemented solely using quantum coherence without entanglement. We demonstrate the protocol by exploiting the high-fidelity quantum state preparation and measurement with a superconducting qubit in the circuit quantum electrodynamics architecture and a nearly quantum-limited parametric amplifier. Our experiment shows the advantage of using quantum coherence of a single qubit for information processing even when multipartite correlation is not present.
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Affiliation(s)
- Xiao Yuan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Ke Liu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Weiting Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuwei Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Fang Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zhaopeng Yan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - R Vijay
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Xiongfeng Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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99
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Wang DW, Cai H, Liu RB, Scully MO. Mesoscopic Superposition States Generated by Synthetic Spin-Orbit Interaction in Fock-State Lattices. PHYSICAL REVIEW LETTERS 2016; 116:220502. [PMID: 27314706 DOI: 10.1103/physrevlett.116.220502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Indexed: 06/06/2023]
Abstract
Mesoscopic superposition states of photons can be prepared in three cavities interacting with the same two-level atom. By periodically modulating the three cavity frequencies around the transition frequency of the atom with a 2π/3 phase difference, the time reversal symmetry is broken and an optical circulator is generated with chiralities depending on the quantum state of the atom. A superposition of the atomic states can guide photons from one cavity to a mesoscopic superposition of the other two cavities. The physics can be understood in a finite spin-orbit-coupled Fock-state lattice where the atom and the cavities carry the spin and the orbit degrees of freedom, respectively. This scheme can be realized in circuit QED architectures and provides a new platform for exploring quantum information and topological physics in novel lattices.
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Affiliation(s)
- Da-Wei Wang
- Texas A&M University, College Station, Texas 77843, USA
| | - Han Cai
- Texas A&M University, College Station, Texas 77843, USA
| | - Ren-Bao Liu
- Department of Physics and Centre for Quantum Coherence, The Chinese University of Hong Kong, Hong Kong, China
| | - Marlan O Scully
- Texas A&M University, College Station, Texas 77843, USA
- Princeton University, Princeton, New Jersey 08544, USA
- Baylor University, Waco, Texas 76706, USA
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100
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Joo J, Ginossar E. Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics. Sci Rep 2016; 6:26338. [PMID: 27245775 PMCID: PMC4887884 DOI: 10.1038/srep26338] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/20/2016] [Indexed: 11/29/2022] Open
Abstract
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.
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Affiliation(s)
- Jaewoo Joo
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - Eran Ginossar
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
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