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Cuzminschi M, Zubarev A, Iordache SM, Isar A. Influence of the seed of measurement on the work extracted in a quantum Szilard engine. iScience 2023; 26:108563. [PMID: 38162018 PMCID: PMC10755042 DOI: 10.1016/j.isci.2023.108563] [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: 08/03/2023] [Revised: 09/20/2023] [Accepted: 11/20/2023] [Indexed: 01/03/2024] Open
Abstract
We investigate the influence of the seed of measurement on the performance of a Szilard engine based on a two-mode Gaussian state evolving in a noisy channel. Quantum work is extracted by performing a positive operator-valued measurement (POVM) on one of the two modes, after which this mode reaches equilibrium with the environment. As the seed of measurement, we use a single-mode squeezed thermal state. We employ the Markovian Kossakowski-Lindblad master equation to determine the evolution in time of the considered open system and the quantum work is defined based on the Rényi entropy of order 2. We show that the extracted quantum work and information-work efficiency strongly depend on the characteristic parameters of the system (frequency, average thermal photons number, and squeezing), the noisy channel (temperature and squeezing of the bath), and the seed of measurement (average thermal photons number and strength of the measurement).
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Affiliation(s)
- Marina Cuzminschi
- Department of Theoretical Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 07125 Magurele, Ilfov, Romania
- Faculty of Physics, University of Bucharest, 077125 Magurele, Ilfov, Romania
| | - Alexei Zubarev
- Plasma Physics and Nuclear Fusion Laboratory, National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania
- Extreme Light Infrastructure, National Institute for Physics and Nuclear Engineering, 07125 Magurele, Ilfov, Romania
| | - Stefan-Marian Iordache
- Optospintronics Department, National Institute for Research and Development for Optoelectronics—INOE 2000, 077125 Magurele, Ilfov, Romania
| | - Aurelian Isar
- Department of Theoretical Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 07125 Magurele, Ilfov, Romania
- Faculty of Physics, University of Bucharest, 077125 Magurele, Ilfov, Romania
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Zhao W, Shi R, Wu X, Wang F, Ruan X. Quantum digital signature with unidimensional continuous-variable against the measurement angular error. OPTICS EXPRESS 2023; 31:17003-17016. [PMID: 37157766 DOI: 10.1364/oe.487849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The continuous-variable quantum digital signature (CV-QDS) scheme relies on the components of quantum key generation protocol (KGP) to negotiate classical signature, which is more compatible with optical fibers. Nevertheless, the measurement angular error of heterodyne detection or homodyne detection will cause security issues when performing KGP in the distribution stage. For that, we propose to utilize unidimensional modulation in KGP components, which only requires to modulate single quadrature and without the process of basis choice. Numerical simulation results show that the security under collective attack, repudiation attack and forgery attack can be guaranteed. We expect that the unidimensional modulation of KGP components could further simplify the implementation of CV-QDS and circumvent the security issues caused by the measurement angular error.
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Cuzminschi M, Zubarev A, Isar A. Extractable quantum work from a two-mode Gaussian state in a noisy channel. Sci Rep 2021; 11:24286. [PMID: 34930993 PMCID: PMC8688490 DOI: 10.1038/s41598-021-03752-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 12/09/2021] [Indexed: 11/10/2022] Open
Abstract
We study a Szilard engine based on a Gaussian state of a system consisting of two bosonic modes placed in a noisy channel. As the initial state of the system is taken an entangled squeezed thermal state, and the quantum work is extracted by performing a measurement on one of the two modes. We use the Markovian Kossakowski-Lindblad master equation for describing the time evolution of the open system and the quantum work definition based on the second order Rényi entropy to simulate the engine. We also study the information-work efficiency of the Szilard engine as a function of the system parameters. The efficiency is defined as the ratio of the extractable work averaged over the measurement angle and the erasure work, which is proportional to the information stored in the system. We show that the extractable quantum work increases with the temperature of the reservoir and the squeezing between the modes, average numbers of thermal photons and frequencies of the modes. The work increases also with the strength of the measurement, attaining the maximal values in the case of a heterodyne detection. The extractable work is decreasing by increasing the squeezing parameter of the noisy channel and it oscillates with the phase of the squeezed thermal reservoir. The efficiency mostly has a similar behavior with the extractable quantum work evolution. However information-work efficiency decreases with temperature, while the quantity of the extractable work increases.
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Affiliation(s)
- Marina Cuzminschi
- Department of Theoretical Physics, National Institute for Physics and Nuclear Engineering, 077125, Magurele-Bucharest, Romania
- Faculty of Physics, University of Bucharest, 077125, Magurele-Bucharest, Romania
| | - Alexei Zubarev
- Plasma Physics and Nuclear Fusion Department, National Institute for Laser, Plasma and Radiation Physics, 077125, Magurele-Bucharest, Romania.
| | - Aurelian Isar
- Department of Theoretical Physics, National Institute for Physics and Nuclear Engineering, 077125, Magurele-Bucharest, Romania
- Faculty of Physics, University of Bucharest, 077125, Magurele-Bucharest, Romania
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Security Analysis of Unidimensional Continuous-Variable Quantum Key Distribution Using Uncertainty Relations. ENTROPY 2018; 20:e20030157. [PMID: 33265248 PMCID: PMC7512673 DOI: 10.3390/e20030157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/22/2018] [Accepted: 02/27/2018] [Indexed: 11/16/2022]
Abstract
We study the equivalence between the entanglement-based scheme and prepare-and-measure scheme of unidimensional (UD) continuous-variable quantum key distribution protocol. Based on this equivalence, the physicality and security of the UD coherent-state protocols in the ideal detection and realistic detection conditions are investigated using the Heisenberg uncertainty relation, respectively. We also present a method to increase both the secret key rates and maximal transmission distances of the UD coherent-state protocol by adding an optimal noise to the reconciliation side. It is expected that our analysis will aid in the practical applications of the UD protocol.
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Abstract
We consider transfer of a highly nonclassical quantum state through an optomechanical system. That is we investigate a protocol consisting of sequential upload, storage and reading out of the quantum state from a mechanical mode of an optomechanical system. We show that provided the input state is in a test-bed single-photon Fock state, the Wigner function of the recovered state can have negative values at the origin, which is a manifest of nonclassicality of the quantum state of the macroscopic mechanical mode and the overall transfer protocol itself. Moreover, we prove that the recovered state is quantum non-Gaussian for wide range of setup parameters. We verify that current electromechanical and optomechanical experiments can test this complete transfer of single photon.
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Rashid M, Tufarelli T, Bateman J, Vovrosh J, Hempston D, Kim MS, Ulbricht H. Experimental Realization of a Thermal Squeezed State of Levitated Optomechanics. PHYSICAL REVIEW LETTERS 2016; 117:273601. [PMID: 28084746 DOI: 10.1103/physrevlett.117.273601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 06/06/2023]
Abstract
We experimentally squeeze the thermal motional state of an optically levitated nanosphere by fast switching between two trapping frequencies. The measured phase-space distribution of the center of mass of our particle shows the typical shape of a squeezed thermal state, from which we infer up to 2.7 dB of squeezing along one motional direction. In these experiments the average thermal occupancy is high and, even after squeezing, the motional state remains in the remit of classical statistical mechanics. Nevertheless, we argue that the manipulation scheme described here could be used to achieve squeezing in the quantum regime if preceded by cooling of the levitated mechanical oscillator. Additionally, a higher degree of squeezing could, in principle, be achieved by repeating the frequency-switching protocol multiple times.
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Affiliation(s)
- Muddassar Rashid
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Tommaso Tufarelli
- School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - James Bateman
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
- Department of Physics, Swansea University, Swansea SA2 8PP, United Kingdom
| | - Jamie Vovrosh
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - David Hempston
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - M S Kim
- QOLS, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hendrik Ulbricht
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom
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Trusted Noise in Continuous-Variable Quantum Key Distribution: A Threat and a Defense. ENTROPY 2016. [DOI: 10.3390/e18010020] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Aspachs M, Adesso G, Fuentes I. Optimal quantum estimation of the Unruh-Hawking effect. PHYSICAL REVIEW LETTERS 2010; 105:151301. [PMID: 21230889 DOI: 10.1103/physrevlett.105.151301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Indexed: 05/30/2023]
Abstract
We address on general quantum-statistical grounds the problem of optimal detection of the Unruh-Hawking effect. We show that the effect signatures are magnified up to potentially observable levels if the scalar field to be probed has high mean energy from an inertial perspective: The Unruh-Hawking effect acts like an amplification channel. We prove that a field in a Fock inertial state, probed via photon counting by a noninertial detector, realizes the optimal strategy attaining the ultimate sensitivity allowed by quantum mechanics for the observation of the effect. We define the parameter regime in which the effect can be reliably revealed in laboratory experiments, regardless of the specific implementation.
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Affiliation(s)
- Mariona Aspachs
- Grup de Física Teòrica, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
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Monras A, Paris MGA. Optimal quantum estimation of loss in bosonic channels. PHYSICAL REVIEW LETTERS 2007; 98:160401. [PMID: 17501396 DOI: 10.1103/physrevlett.98.160401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Indexed: 05/15/2023]
Abstract
We address the estimation of the loss parameter of a bosonic channel probed by Gaussian signals. We derive the ultimate quantum bound with precision and show that no improvement may be obtained by having access to the environmental degrees of freedom. We find that, for small losses, the variance of the optimal estimator is proportional to the loss parameter itself, a result that represents a qualitative improvement over the shot-noise limit. An observable based on the symmetric logarithmic derivative is obtained, which attains the ultimate bound and may be implemented using Gaussian operations and photon counting.
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Affiliation(s)
- Alex Monras
- Grup de Fisica Teòrica & IFAE, Universitat Autònoma de Barcelona, Bellaterra E-08193, Spain
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D’Auria V, Porzio A, Solimeno S, Olivares S, Paris MGA. Characterization of bipartite states using a single homodyne detector. ACTA ACUST UNITED AC 2005. [DOI: 10.1088/1464-4266/7/12/044] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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