1
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Dogra S, McCord JJ, Paraoanu GS. Coherent interaction-free detection of microwave pulses with a superconducting circuit. Nat Commun 2022; 13:7528. [PMID: 36476574 PMCID: PMC9729670 DOI: 10.1038/s41467-022-35049-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 11/16/2022] [Indexed: 12/12/2022] Open
Abstract
The interaction-free measurement is a fundamental quantum effect whereby the presence of a photosensitive object is determined without irreversible photon absorption. Here we propose the concept of coherent interaction-free detection and demonstrate it experimentally using a three-level superconducting transmon circuit. In contrast to standard interaction-free measurement setups, where the dynamics involves a series of projection operations, our protocol employs a fully coherent evolution that results, surprisingly, in a higher probability of success. We show that it is possible to ascertain the presence of a microwave pulse resonant with the second transition of the transmon, while at the same time avoid exciting the device onto the third level. Experimentally, this is done by using a series of Ramsey microwave pulses coupled into the first transition and monitoring the ground-state population.
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Affiliation(s)
- Shruti Dogra
- grid.5373.20000000108389418QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - John J. McCord
- grid.5373.20000000108389418QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - Gheorghe Sorin Paraoanu
- grid.5373.20000000108389418QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
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2
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Hong S, Kim YS, Cho YW, Kim J, Lee SW, Lim HT. Demonstration of Complete Information Trade-Off in Quantum Measurement. PHYSICAL REVIEW LETTERS 2022; 128:050401. [PMID: 35179912 DOI: 10.1103/physrevlett.128.050401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
While an information-disturbance trade-off in quantum measurement has been at the core of foundational quantum physics and constitutes a basis of secure quantum information processing, recently verified reversibility of a quantum measurement requires to refine it toward a complete version of information trade-off in quantum measurement. Here we experimentally demonstrate a trade-off relation among all information contents, i.e., information gain, disturbance, and reversibility in quantum measurement. By exploring quantum measurements applied on a photonic qutrit, we observe that the information of a quantum state is split into three distinct parts accounting for the extracted, disturbed, and reversible information. We verify that such different parts of information are in trade-off relations not only pairwise but also triplewise all at once, and find that the triplewise relation is tighter than any of the pairwise relations. Finally, we realize optimal quantum measurements that inherently preserve quantum information without loss of information, which offer wider applications in measurement-based quantum information processing.
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Affiliation(s)
- Seongjin Hong
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Yong-Su Kim
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
| | - Young-Wook Cho
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- Department of Physics, Yonsei University, Seoul 03722, Korea
| | - Jaewan Kim
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Seung-Woo Lee
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Hyang-Tag Lim
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
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3
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Harrington PM, Tan D, Naghiloo M, Murch KW. Characterizing a Statistical Arrow of Time in Quantum Measurement Dynamics. PHYSICAL REVIEW LETTERS 2019; 123:020502. [PMID: 31386500 DOI: 10.1103/physrevlett.123.020502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 04/02/2019] [Indexed: 06/10/2023]
Abstract
In both thermodynamics and quantum mechanics, the arrow of time is characterized by the statistical likelihood of physical processes. We characterize this arrow of time for the continuous quantum measurement dynamics of a superconducting qubit. By experimentally tracking individual weak measurement trajectories, we compare the path probabilities of forward and backward-in-time evolution to develop an arrow of time statistic associated with measurement dynamics. We compare the statistics of individual trajectories to ensemble properties showing that the measurement dynamics obeys both detailed and integral fluctuation theorems, thus establishing the consistency between microscopic and macroscopic measurement dynamics.
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Affiliation(s)
- P M Harrington
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - D Tan
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - M Naghiloo
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - K W Murch
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Institute for Materials Science and Engineering, St. Louis, Missouri 63130, USA
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4
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Enhanced Superdense Coding over Correlated Amplitude Damping Channel. ENTROPY 2019; 21:e21060598. [PMID: 33267312 PMCID: PMC7515104 DOI: 10.3390/e21060598] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/09/2019] [Accepted: 06/13/2019] [Indexed: 11/17/2022]
Abstract
Quantum channels with correlated effects are realistic scenarios for the study of noisy quantum communication when the channels are consecutively used. In this paper, superdense coding is reexamined under a correlated amplitude damping (CAD) channel. Two techniques named as weak measurement and environment-assisted measurement are utilized to enhance the capacity of superdense coding. The results show that both of them enable us to battle against the CAD decoherence and improve the capacity with a certain probability. Remarkably, the scheme of environment-assisted measurement always outperforms the scheme of weak measurement in both improving the capacity and successful probability. These notable superiorities could be attributed to the fact that environment-assisted measurement can extract additional information from the environment and thus it performs much better.
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5
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Bülte J, Bednorz A, Bruder C, Belzig W. Noninvasive Quantum Measurement of Arbitrary Operator Order by Engineered Non-Markovian Detectors. PHYSICAL REVIEW LETTERS 2018; 120:140407. [PMID: 29694141 DOI: 10.1103/physrevlett.120.140407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/30/2017] [Indexed: 06/08/2023]
Abstract
The development of solid-state quantum technologies requires the understanding of quantum measurements in interacting, nonisolated quantum systems. In general, a permanent coupling of detectors to a quantum system leads to memory effects that have to be taken into account in interpreting the measurement results. We analyze a generic setup of two detectors coupled to a quantum system and derive a compact formula in the weak-measurement limit that interpolates between an instantaneous (text-book type) and almost continuous-detector dynamics-dependent-measurement. A quantum memory effect that we term "system-mediated detector-detector interaction" is crucial to observe noncommuting observables simultaneously. Finally, we propose a mesoscopic double-dot detector setup in which the memory effect is tunable and that can be used to explore the transition to non-Markovian quantum measurements experimentally.
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Affiliation(s)
- Johannes Bülte
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
| | - Adam Bednorz
- Faculty of Physics, University of Warsaw, Pasteura 5, PL02-093 Warsaw, Poland
| | - Christoph Bruder
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
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6
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Hacohen-Gourgy S, García-Pintos LP, Martin LS, Dressel J, Siddiqi I. Incoherent Qubit Control Using the Quantum Zeno Effect. PHYSICAL REVIEW LETTERS 2018; 120:020505. [PMID: 29376684 DOI: 10.1103/physrevlett.120.020505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Indexed: 06/07/2023]
Abstract
The quantum Zeno effect is the suppression of Hamiltonian evolution by repeated observation, which pins the system to an eigenstate of the measurement observable. Using measurement alone, control of the state can be achieved if the observable is slowly varied, so that the state tracks the now time-dependent eigenstate. We demonstrate this using a circuit-QED readout technique that couples to a dynamically controllable observable of a qubit. Continuous monitoring of the measurement record allows us to detect an escape from the eigenstate, thus serving as a built-in form of error detection. We show this by postselecting on realizations with high fidelity with respect to the target state. Our dynamical measurement operator technique offers a new tool for numerous forms of quantum feedback protocols, including adaptive measurements and rapid state purification.
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Affiliation(s)
- S Hacohen-Gourgy
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA
- Center for Quantum Coherent Science, Department of Physics, University of California, Berkeley, California 94720, USA
| | - L P García-Pintos
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA
| | - L S Martin
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA
- Center for Quantum Coherent Science, Department of Physics, University of California, Berkeley, California 94720, USA
| | - J Dressel
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA
| | - I Siddiqi
- Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA
- Center for Quantum Coherent Science, Department of Physics, University of California, Berkeley, California 94720, USA
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7
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Mastriani M. Optimal Estimate of Quantum States. JOURNAL OF APPLIED MATHEMATICS AND PHYSICS 2018; 06:1363-1381. [DOI: 10.4236/jamp.2018.66114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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8
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Dressel J, Chantasri A, Jordan AN, Korotkov AN. Arrow of Time for Continuous Quantum Measurement. PHYSICAL REVIEW LETTERS 2017; 119:220507. [PMID: 29286799 DOI: 10.1103/physrevlett.119.220507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Indexed: 06/07/2023]
Abstract
We investigate the statistical arrow of time for a quantum system being monitored by a sequence of measurements. For a continuous qubit measurement example, we demonstrate that time-reversed evolution is always physically possible, provided that the measurement record is also negated. Despite this restoration of dynamical reversibility, a statistical arrow of time emerges, and may be quantified by the log-likelihood difference between forward and backward propagation hypotheses. We then show that such reversibility is a universal feature of nonprojective measurements, with forward or backward Janus measurement sequences that are time-reversed inverses of each other.
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Affiliation(s)
- Justin Dressel
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA
| | - Areeya Chantasri
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
- Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
- Centre for Quantum Dynamics, Griffith University, Nathan QLD 4111, Australia
| | - Andrew N Jordan
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
- Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Alexander N Korotkov
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
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9
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Wendin G. Quantum information processing with superconducting circuits: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:106001. [PMID: 28682303 DOI: 10.1088/1361-6633/aa7e1a] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of quantum supremacy with fifty qubits is anticipated in just a few years. Quantum supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of superconducting devices, systems and applications. As such, the discussion of superconducting qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry.
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Affiliation(s)
- G Wendin
- Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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10
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Chen Y, Zou J, Long ZW, Shao B. Protecting quantum Fisher information of N-qubit GHZ state by weak measurement with flips against dissipation. Sci Rep 2017; 7:6160. [PMID: 28733578 PMCID: PMC5522470 DOI: 10.1038/s41598-017-04726-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/08/2017] [Indexed: 11/09/2022] Open
Abstract
In this paper we propose a scheme by using weak-measurement-based pre- and post-flips (WMPPF) to protect the average quantum Fisher information (QFI) in the independent amplitude-damping channel (ADC) for N-qubit GHZ state and generalized N-qubit GHZ states. We also discuss the weak measurement and quantum measurement reversal (WMQMR) with the same ADC. Based on the analytical and numerical results we obtain the main result: the WMPPF can reduce the effect of dissipation on the average QFI of the phase or the frequency for GHZ state and some generalized GHZ states, and the WMQMR can reduce the effect of dissipation on the average fidelity for GHZ state and generalized GHZ states in ADC. Comparing QFI with fidelity for WMPPF or for WMQMR, a scheme protecting the average fidelity does not necessarily protect the average QFI, even with the same parameters, and vice versa. We also focus on the average QFI versus N in the phase estimation and the frequency estimation of WMPPF, both of which show the advantages over the do-nothing (DN) case. From the investigation of the QFI of weight factor, we find that increasing qubit number can protect it both for WMPPF and for DN.
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Affiliation(s)
- Yu Chen
- School of Physics, Beijing Institute of Technology, Beijing, 100081, China. .,School of Physics and Electronic science, Guizhou Normal College, Guiyang, 550018, China.
| | - Jian Zou
- School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Zheng-Wen Long
- College of Physics, Guizhou University, Guiyang, 550025, China
| | - Bin Shao
- School of Physics, Beijing Institute of Technology, Beijing, 100081, China
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11
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Mastriani M. Quantum image processing? QUANTUM INFORMATION PROCESSING 2017; 16:27. [DOI: 10.1007/s11128-016-1457-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 11/08/2016] [Indexed: 09/02/2023]
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12
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Wang XW, Yu S, Zhang DY, Oh CH. Effect of weak measurement on entanglement distribution over noisy channels. Sci Rep 2016; 6:22408. [PMID: 26935775 PMCID: PMC4776117 DOI: 10.1038/srep22408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/12/2016] [Indexed: 11/24/2022] Open
Abstract
Being able to implement effective entanglement distribution in noisy environments is a key step towards practical quantum communication, and long-term efforts have been made on the development of it. Recently, it has been found that the null-result weak measurement (NRWM) can be used to enhance probabilistically the entanglement of a single copy of amplitude-damped entangled state. This paper investigates remote distributions of bipartite and multipartite entangled states in the amplitudedamping environment by combining NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has no positive effect on the distribution of bipartite maximally entangled states and multipartite Greenberger-Horne-Zeilinger states, although it is able to increase the amount of entanglement of each source state (noisy entangled state) of EDPs with a certain probability. However, we find that the NRWM would contribute to remote distributions of multipartite W states. We demonstrate that the NRWM can not only reduce the fidelity thresholds for distillability of decohered W states, but also raise the distillation efficiencies of W states. Our results suggest a new idea for quantifying the ability of a local filtering operation in protecting entanglement from decoherence.
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Affiliation(s)
- Xin-Wen Wang
- College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, China
- Center for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Sixia Yu
- Center for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Deng-Yu Zhang
- College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang 421002, China
| | - C. H. Oh
- Center for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542
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13
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Su F, Man ZX. Controlling Coherence Transfer of Dimer Interacting with Independent Environments. CHINESE J CHEM PHYS 2015. [DOI: 10.1063/1674-0068/28/cjcp1503036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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14
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Probabilistic Teleportation via Quantum Channel with Partial Information. ENTROPY 2015. [DOI: 10.3390/e17063621] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Lim HT, Lee JC, Hong KH, Kim YH. Avoiding entanglement sudden death using single-qubit quantum measurement reversal. OPTICS EXPRESS 2014; 22:19055-19068. [PMID: 25320992 DOI: 10.1364/oe.22.019055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
When two entangled qubits, each owned by Alice and Bob, undergo separate decoherence, the amount of entanglement is reduced, and often, weak decoherence causes complete loss of entanglement, known as entanglement sudden death. Here we show that it is possible to apply quantum measurement reversal on a single-qubit to avoid entanglement sudden death, rather than on both qubits. Our scheme has important applications in quantum information processing protocols based on distributed or stored entangled qubits as they are subject to decoherence.
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16
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Reducing the impact of intrinsic dissipation in a superconducting circuit by quantum error detection. Nat Commun 2014; 5:3135. [DOI: 10.1038/ncomms4135] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/17/2013] [Indexed: 11/08/2022] Open
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17
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Observing single quantum trajectories of a superconducting quantum bit. Nature 2013; 502:211-4. [PMID: 24108052 DOI: 10.1038/nature12539] [Citation(s) in RCA: 258] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/07/2013] [Indexed: 11/08/2022]
Abstract
The length of time that a quantum system can exist in a superposition state is determined by how strongly it interacts with its environment. This interaction entangles the quantum state with the inherent fluctuations of the environment. If these fluctuations are not measured, the environment can be viewed as a source of noise, causing random evolution of the quantum system from an initially pure state into a statistical mixture--a process known as decoherence. However, by accurately measuring the environment in real time, the quantum system can be maintained in a pure state and its time evolution described by a 'quantum trajectory' determined by the measurement outcome. Here we use weak measurements to monitor a microwave cavity containing a superconducting quantum bit (qubit), and track the individual quantum trajectories of the system. In this set-up, the environment is dominated by the fluctuations of a single electromagnetic mode of the cavity. Using a near-quantum-limited parametric amplifier, we selectively measure either the phase or the amplitude of the cavity field, and thereby confine trajectories to either the equator or a meridian of the Bloch sphere. We perform quantum state tomography at discrete times along the trajectory to verify that we have faithfully tracked the state of the quantum system as it diffuses on the surface of the Bloch sphere. Our results demonstrate that decoherence can be mitigated by environmental monitoring, and validate the foundation of quantum feedback approaches based on Bayesian statistics. Moreover, our experiments suggest a new means of implementing 'quantum steering'--the harnessing of action at a distance to manipulate quantum states through measurement.
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18
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Sherman JA, Curtis MJ, Szwer DJ, Allcock DTC, Imreh G, Lucas DM, Steane AM. Experimental recovery of a qubit from partial collapse. PHYSICAL REVIEW LETTERS 2013; 111:180501. [PMID: 24237494 DOI: 10.1103/physrevlett.111.180501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Indexed: 06/02/2023]
Abstract
We describe and implement a method to restore the state of a single qubit, in principle perfectly, after it has partially collapsed. The method resembles the classical Hahn spin echo but works on a wider class of relaxation processes, in which the quantum state partially leaves the computational Hilbert space. It is not guaranteed to work every time, but successful outcomes are heralded. We demonstrate, using a single trapped ion, a better performance from this recovery method than can be obtained employing projection and postselection alone. The demonstration features a novel qubit implementation that permits both partial collapse and coherent manipulations with high fidelity.
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Affiliation(s)
- J A Sherman
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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19
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20
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Groen JP, Ristè D, Tornberg L, Cramer J, de Groot PC, Picot T, Johansson G, DiCarlo L. Partial-measurement backaction and nonclassical weak values in a superconducting circuit. PHYSICAL REVIEW LETTERS 2013; 111:090506. [PMID: 24033014 DOI: 10.1103/physrevlett.111.090506] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 06/29/2013] [Indexed: 06/02/2023]
Abstract
We realize indirect partial measurement of a transmon qubit in circuit quantum electrodynamics by interaction with an ancilla qubit and projective ancilla measurement with a dedicated readout resonator. Accurate control of the interaction and ancilla measurement basis allows tailoring the measurement strength and operator. The tradeoff between measurement strength and qubit backaction is characterized through the distortion of a qubit Rabi oscillation imposed by ancilla measurement in different bases. Combining partial and projective qubit measurements, we provide the solid-state demonstration of the correspondence between a nonclassical weak value and the violation of a Leggett-Garg inequality.
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Affiliation(s)
- J P Groen
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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21
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Bednorz A, Bruder C, Reulet B, Belzig W. Nonsymmetrized correlations in quantum noninvasive measurements. PHYSICAL REVIEW LETTERS 2013; 110:250404. [PMID: 23829718 DOI: 10.1103/physrevlett.110.250404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Indexed: 06/02/2023]
Abstract
A long-standing problem in quantum mesoscopic physics is which operator order corresponds to noise expressions like <I(-ω)I(ω)>, where I(ω) is the measured current at frequency ω. Symmetrized order describes a classical measurement while nonsymmetrized order corresponds to a quantum detector, e.g., one sensitive to either emission or absorption of photons. We show that both order schemes can be embedded in quantum weak-measurement theory taking into account measurements with memory, characterized by a memory function which is independent of a particular experimental detection scheme. We discuss the resulting quasiprobabilities for different detector temperatures and how their negativity can be tested on the level of second-order correlation functions already. Experimentally, this negativity can be related to the squeezing of the many-body state of the transported electrons in an ac-driven tunnel junction.
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Affiliation(s)
- Adam Bednorz
- Faculty of Physics, University of Warsaw, ul. Hoża 69, PL00-681 Warsaw, Poland.
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22
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Biological complexity, quantum coherent states and the problem of efficient transmission of information inside a cell. Biosystems 2013; 111:190-8. [DOI: 10.1016/j.biosystems.2013.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 01/31/2013] [Accepted: 02/06/2013] [Indexed: 01/30/2023]
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23
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Schindler P, Monz T, Nigg D, Barreiro JT, Martinez EA, Brandl MF, Chwalla M, Hennrich M, Blatt R. Undoing a quantum measurement. PHYSICAL REVIEW LETTERS 2013; 110:070403. [PMID: 25166354 DOI: 10.1103/physrevlett.110.070403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Indexed: 06/03/2023]
Abstract
In general, a quantum measurement yields an undetermined answer and alters the system to be consistent with the measurement result. This process maps multiple initial states into a single state and thus cannot be reversed. This has important implications in quantum information processing, where errors can be interpreted as measurements. Therefore, it seems that it is impossible to correct errors in a quantum information processor, but protocols exist that are capable of eliminating them if they affect only part of the system. In this work we present the deterministic reversal of a fully projective measurement on a single particle, enabled by a quantum error-correction protocol in a trapped ion quantum information processor. We further introduce an in-sequence, single-species recooling procedure to counteract the motional heating of the ion string due to the measurement.
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Affiliation(s)
- Philipp Schindler
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Thomas Monz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Daniel Nigg
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Julio T Barreiro
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Esteban A Martinez
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Matthias F Brandl
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Michael Chwalla
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria and Institut für Quantenoptik und Quanteninformation der Österreichischen Akademie der Wissenschaften, Technikerstrasse 21a, A-6020 Innsbruck, Austria
| | - Markus Hennrich
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Rainer Blatt
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria and Institut für Quantenoptik und Quanteninformation der Österreichischen Akademie der Wissenschaften, Technikerstrasse 21a, A-6020 Innsbruck, Austria
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Cheong YW, Lee SW. Balance between information gain and reversibility in weak measurement. PHYSICAL REVIEW LETTERS 2012; 109:150402. [PMID: 23102278 DOI: 10.1103/physrevlett.109.150402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/04/2012] [Indexed: 06/01/2023]
Abstract
We derive a tight bound between the quality of estimating a quantum state by measurement and the success probability of undoing the measurement in arbitrary dimensional systems, which completely describes the tradeoff relation between the information gain and reversibility. In this formulation, it is clearly shown that the information extracted from a weak measurement is erased through the reversing process. Our result broadens the information-theoretic perspective on quantum measurement as well as provides a standard tool to characterize weak measurements and reversals.
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Lee JC, Jeong YC, Kim YS, Kim YH. Experimental demonstration of decoherence suppression via quantum measurement reversal. OPTICS EXPRESS 2011; 19:16309-16316. [PMID: 21934994 DOI: 10.1364/oe.19.016309] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Taming decoherence is essential in realizing quantum computation and quantum communication. Here we experimentally demonstrate that decoherence due to amplitude damping can be suppressed by exploiting quantum measurement reversal in which a weak measurement and the reversing measurement are introduced before and after the decoherence channel, respectively. We have also investigated the trade-off relation between the degree of decoherence suppression and the channel transmittance.
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Affiliation(s)
- Jong-Chan Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea
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26
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Ruskov R, Korotkov AN, Mølmer K. Qubit state monitoring by measurement of three complementary observables. PHYSICAL REVIEW LETTERS 2010; 105:100506. [PMID: 20867502 DOI: 10.1103/physrevlett.105.100506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Indexed: 05/29/2023]
Abstract
We consider the evolution of a qubit (spin 1/2) under the simultaneous continuous measurement of three noncommuting qubit operators σ(x), σ(y), and σ(z). For identical ideal detectors, the qubit state evolves by approaching a pure state with a random direction in the Bloch vector space and by undergoing locally isotropic diffusion in the perpendicular directions. The quantum state conditioned on the complete detector record is used to assess the fidelity of classically inspired estimates based on running time averages and discrete time bin detector outputs.
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Affiliation(s)
- Rusko Ruskov
- Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark
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27
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Gillett GG, Dalton RB, Lanyon BP, Almeida MP, Barbieri M, Pryde GJ, O'Brien JL, Resch KJ, Bartlett SD, White AG. Experimental feedback control of quantum systems using weak measurements. PHYSICAL REVIEW LETTERS 2010; 104:080503. [PMID: 20366921 DOI: 10.1103/physrevlett.104.080503] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Indexed: 05/29/2023]
Abstract
A goal of the emerging field of quantum control is to develop methods for quantum technologies to function robustly in the presence of noise. Central issues are the fundamental limitations on the available information about quantum systems and the disturbance they suffer in the process of measurement. In the context of a simple quantum control scenario-the stabilization of nonorthogonal states of a qubit against dephasing-we experimentally explore the use of weak measurements in feedback control. We find that, despite the intrinsic difficultly of implementing them, weak measurements allow us to control the qubit better in practice than is even theoretically possible without them. Our work shows that these more general quantum measurements can play an important role for feedback control of quantum systems.
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Affiliation(s)
- G G Gillett
- Department of Physics and Centre for Quantum Computer Technology, The University of Queensland, Brisbane 4072, Australia.
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28
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Kim YS, Cho YW, Ra YS, Kim YH. Reversing the weak quantum measurement for a photonic qubit. OPTICS EXPRESS 2009; 17:11978-11985. [PMID: 19582113 DOI: 10.1364/oe.17.011978] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate the conditional reversal of a weak (partial-collapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state after a successful reversing operation. Both the weak measurement and the reversal operation are implemented linear optically. The state recovery fidelity, determined by quantum process tomography, is shown to be over 94% for partial-collapse strength up to 0.9. We also experimentally study information gain due to the weak measurement and discuss the role of the reversing operation as an information erasure.
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Affiliation(s)
- Yong-Su Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea.
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29
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Nigg SE, Büttiker M. Universal detector efficiency of a mesoscopic capacitor. PHYSICAL REVIEW LETTERS 2009; 102:236801. [PMID: 19658955 DOI: 10.1103/physrevlett.102.236801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Indexed: 05/28/2023]
Abstract
We investigate theoretically a novel type of high frequency quantum detector based on the mesoscopic capacitor recently realized by Gabelli et al. [Science 313, 499 (2006)10.1126/science.1126940], which consists of a quantum dot connected via a single channel quantum point contact to a single lead. We show that the state of a double quantum dot charge qubit capacitively coupled to this detector can be readout in the GHz frequency regime with near quantum limited efficiency. To leading order, the quantum efficiency is found to be universal owing to the universality of the charge relaxation resistance of the mesoscopic capacitor.
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Affiliation(s)
- Simon E Nigg
- Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland.
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