101
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Stottmeister A, Osborne TJ. On the renormalization group fixed point of the two-dimensional Ising model at criticality. Sci Rep 2023; 13:14859. [PMID: 37684323 PMCID: PMC10491843 DOI: 10.1038/s41598-023-42005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 09/04/2023] [Indexed: 09/10/2023] Open
Abstract
We analyze the renormalization group fixed point of the two-dimensional Ising model at criticality. In contrast with expectations from tensor network renormalization (TNR), we show that a simple, explicit analytic description of this fixed point using operator-algebraic renormalization (OAR) is possible. Specifically, the fixed point is characterized in terms of spin-spin correlation functions. Explicit error bounds for the approximation of continuum correlation functions are given.
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Affiliation(s)
- Alexander Stottmeister
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167, Hannover, Germany.
| | - Tobias J Osborne
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167, Hannover, Germany
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102
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Li X. Optimal control of quantum state preparation and entanglement creation in two-qubit quantum system with bounded amplitude. Sci Rep 2023; 13:14734. [PMID: 37679384 PMCID: PMC10484962 DOI: 10.1038/s41598-023-41688-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023] Open
Abstract
We consider the optimal control problem in a two-qubit system with bounded amplitude. Two cases are studied: quantum state preparation and entanglement creation. Cost functions, fidelity and concurrence, are optimized over bang-off controls for various values of the total duration, respectively. For quantum state preparation problem, three critical time points are determined accurately, and optimal controls are estimated. A better estimation of the quantum speed limit is obtained, so is the time-optimal control. For entanglement creation problem, two critical time points are determined, one of them is the minimal time to achieve maximal entanglement (unit concurrence) starting from the product state. In addition, the comparisons between bang-off and chopped random basis (CRAB) are made.
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Affiliation(s)
- Xikun Li
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei, 230601, China.
- Max-Planck-Institut für Physik komplexer Systeme, 01187, Dresden, Germany.
- Department of Physics and Astronomy, Aarhus University, 8000, Aarhus, Denmark.
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103
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Shiratori H, Shinkawa H, Röhm A, Chauvet N, Segawa E, Laurent J, Bachelier G, Yamagami T, Horisaki R, Naruse M. Asymmetric quantum decision-making. Sci Rep 2023; 13:14636. [PMID: 37670023 PMCID: PMC10480193 DOI: 10.1038/s41598-023-41715-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/30/2023] [Indexed: 09/07/2023] Open
Abstract
Collective decision-making plays a crucial role in information and communication systems. However, decision conflicts among agents often impede the maximization of potential utilities within the system. Quantum processes have shown promise in achieving conflict-free joint decisions between two agents through the entanglement of photons or the quantum interference of orbital angular momentum (OAM). Nonetheless, previous studies have shown symmetric resultant joint decisions, which, while preserving equality, fail to address disparities. In light of global challenges such as ethics and equity, it is imperative for decision-making systems to not only maintain existing equality but also address and resolve disparities. In this study, we investigate asymmetric collective decision-making theoretically and numerically using quantum interference of photons carrying OAM or entangled photons. We successfully demonstrate the realization of asymmetry; however, it should be noted that a certain degree of photon loss is inevitable in the proposed models. We also provide an analytical formulation for determining the available range of asymmetry and describe a method for obtaining the desired degree of asymmetry.
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Affiliation(s)
- Honoka Shiratori
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan.
| | - Hiroaki Shinkawa
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
| | - André Röhm
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
| | - Nicolas Chauvet
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
| | - Etsuo Segawa
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-1 Tokiwadai, Hodogaya, Yokohama, Kanagawa, 240-8501, Japan
| | - Jonathan Laurent
- CNRS, Institut Néel, Université Grenoble Alpes, Grenoble, 38042, France
| | | | - Tomoki Yamagami
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
| | - Ryoichi Horisaki
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
| | - Makoto Naruse
- Department of Information Physics and Computing, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan
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104
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Jun K. A highly accurate quantum optimization algorithm for CT image reconstruction based on sinogram patterns. Sci Rep 2023; 13:14407. [PMID: 37658158 PMCID: PMC10474150 DOI: 10.1038/s41598-023-41700-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 08/30/2023] [Indexed: 09/03/2023] Open
Abstract
Computed tomography (CT) has been developed as a nondestructive technique for observing minute internal images in samples. It has been difficult to obtain photorealistic (clean or clear) CT images due to various unwanted artifacts generated during the CT scanning process, along with the limitations of back-projection algorithms. Recently, an iterative optimization algorithm has been developed that uses an entire sinogram to reduce errors caused by artifacts. In this paper, we introduce a new quantum algorithm for reconstructing CT images. This algorithm can be used with any type of light source as long as the projection is defined. Assuming an experimental sinogram produced by a Radon transform, to find the CT image of this sinogram, we express the CT image as a combination of qubits. After acquiring the Radon transform of the undetermined CT image, we combine the actual sinogram and the optimized qubits. The global energy optimization value used here can determine the value of qubits through a gate model quantum computer or quantum annealer. In particular, the new algorithm can also be used for cone-beam CT image reconstruction and for medical imaging.
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105
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Zhou L, Lin J, Jing Y, Yuan Z. Author Correction: Twin-field quantum key distribution without optical frequency dissemination. Nat Commun 2023; 14:5263. [PMID: 37644020 PMCID: PMC10465689 DOI: 10.1038/s41467-023-40945-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023] Open
Affiliation(s)
- Lai Zhou
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Jinping Lin
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Yumang Jing
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Zhiliang Yuan
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
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106
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Metger T, Renner R. Security of quantum key distribution from generalised entropy accumulation. Nat Commun 2023; 14:5272. [PMID: 37644010 PMCID: PMC10465525 DOI: 10.1038/s41467-023-40920-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/16/2023] [Indexed: 08/31/2023] Open
Abstract
The goal of quantum key distribution (QKD) is to establish a secure key between two parties connected by an insecure quantum channel. To use a QKD protocol in practice, one has to prove that a finite size key is secure against general attacks: no matter the adversary's attack, they cannot gain useful information about the key. A much simpler task is to prove security against collective attacks, where the adversary is assumed to behave identically and independently in each round. In this work, we provide a formal framework for general QKD protocols and show that for any protocol that can be expressed in this framework, security against general attacks reduces to security against collective attacks, which in turn reduces to a numerical computation. Our proof relies on a recently developed information-theoretic tool called generalised entropy accumulation and can handle generic prepare-and-measure protocols directly without switching to an entanglement-based version.
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Affiliation(s)
- Tony Metger
- Institute for Theoretical Physics, ETH Zürich, 8093, Zürich, Switzerland.
| | - Renato Renner
- Institute for Theoretical Physics, ETH Zürich, 8093, Zürich, Switzerland
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107
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Mekonnen HD, Tesfahannes TG, Darge TY, Kumela AG. Quantum correlation in a nano-electro-optomechanical system enhanced by an optical parametric amplifier and Coulomb-type interaction. Sci Rep 2023; 13:13800. [PMID: 37612322 PMCID: PMC10447484 DOI: 10.1038/s41598-023-40490-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 08/10/2023] [Indexed: 08/25/2023] Open
Abstract
In this paper, we investigated the quantum correlation of nano-electro-optomechanical system enhanced by an optical parametric amplifier (OPA) and Coulomb-type interaction. In particular, we consider a hybrid system consisting of a cavity and two charged mechanical oscillators with an OPA, where the optical cavity mode is coupled with a charged mechanical oscillator via radiation pressure, and the two charged mechanical oscillators are coupled through a Coulomb interaction. We use logarithmic negativity to quantify quantum entanglement, and quantum discord to measure the quantumness correlation between the two mechanical oscillators. We characterize quantum steering using the steerability between the two mechanical oscillators. Our results show that the presence of OPA and strong Coulomb coupling enhances the quantum correlations between the two mechanical oscillators. In addition, Coulomb interactions are more prominent in quantum correlations. Besides, in the presence of OPA, the maximum amount of quantum entanglement, quantum steering, and quantum discord were achieved between the two mechanical oscillators is greater than in the absence of OPA. Moreover, a proper phase choice of the optical field driving the OPA enhances quantum correlations under suitable conditions. We obtain quantum entanglement confines quantum steering and quantum discord beyond entanglement. Furthermore, quantum entanglement, quantum steering, and quantum discord decrease rapidly with increasing temperature as a result of decoherence. In addition, quantum discord persists at higher temperature values, although the quantum entanglement between the systems also vanishes completely. Our proposed scheme enhances quantum correlation and proves robust against fluctuations in the bath environment. We believe that the present scheme of quantum correlation provides a promising platform for the realization of continuous variable quantum information processing.
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Affiliation(s)
- Habtamu Dagnaw Mekonnen
- Department of Applied Physics, Adama Science and Technology University, P.O.Box 1888, Adama, Ethiopia
- Department of Physics, Injibara University, P.O.Box 040, Injibara, Ethiopia
| | | | - Tewodros Yirgashewa Darge
- Department of Applied Physics, Adama Science and Technology University, P.O.Box 1888, Adama, Ethiopia
| | - Alemayehu Getahun Kumela
- Department of Applied Physics, Adama Science and Technology University, P.O.Box 1888, Adama, Ethiopia
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108
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Das S, Caruso F. A hybrid-qudit representation of digital RGB images. Sci Rep 2023; 13:13671. [PMID: 37608205 PMCID: PMC10444894 DOI: 10.1038/s41598-023-39906-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 08/01/2023] [Indexed: 08/24/2023] Open
Abstract
Quantum image processing is an emerging topic in the field of quantum information and technology. In this paper, we propose a new quantum image representation of RGB images with deterministic image retrieval, which is an improvement over all the similar existing representations in terms of using minimum resource. We use two entangled quantum registers constituting of total 7 qutrits to encode the color channels and their intensities. Additionally, we generalize the existing encoding methods by using both qubits and qutrits to encode the pixel positions of a rectangular image. This hybrid-qudit approach aligns well with the current progress of NISQ devices in incorporating higher dimensional quantum systems than qubits. We then describe the image encoding method using higher-order qubit-qutrit gates, and demonstrate the decomposition of these gates in terms of simpler elementary gates. We use the Google Cirq's quantum simulator to verify the image preparation in both the ideal noise-free scenario and in presence of realistic noise modelling. We show that the complexity of the image encoding process is linear in the number of pixels. Lastly, we discuss the image compression and some basic RGB image processing protocols using our representation.
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Affiliation(s)
- Sreetama Das
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, Sesto Fiorentino, 50019, Italy.
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Via Nello Carrara 1, Sesto Fiorentino, 50019, Italy.
| | - Filippo Caruso
- Department of Physics and Astronomy, University of Florence, Via Sansone 1, Sesto Fiorentino, 50019, Italy
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Via Nello Carrara 1, Sesto Fiorentino, 50019, Italy
- QSTAR and CNR-INO, Largo Enrico Fermi 2, 50125, Firenze, Italy
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109
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Schiansky P, Kalb J, Sztatecsny E, Roehsner MC, Guggemos T, Trenti A, Bozzio M, Walther P. Author Correction: Demonstration of quantum-digital payments. Nat Commun 2023; 14:5059. [PMID: 37604807 PMCID: PMC10442330 DOI: 10.1038/s41467-023-40866-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023] Open
Affiliation(s)
- Peter Schiansky
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Julia Kalb
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Esther Sztatecsny
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Marie-Christine Roehsner
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
- Security and Communication Technologies, Center for Digital Safety and Security, AIT Austrian Institute of Technology GmbH, Giefinggasse 4, 1210, Vienna, Austria
| | - Tobias Guggemos
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Alessandro Trenti
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
- Security and Communication Technologies, Center for Digital Safety and Security, AIT Austrian Institute of Technology GmbH, Giefinggasse 4, 1210, Vienna, Austria
| | - Mathieu Bozzio
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria.
| | - Philip Walther
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria.
- Christian Doppler Laboratory for Photonic Quantum Computer, Faculty of Physics, University of Vienna, 1090, Vienna, Austria.
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110
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Helsen J, Ioannou M, Kitzinger J, Onorati E, Werner AH, Eisert J, Roth I. Shadow estimation of gate-set properties from random sequences. Nat Commun 2023; 14:5039. [PMID: 37598209 PMCID: PMC10439944 DOI: 10.1038/s41467-023-39382-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 06/12/2023] [Indexed: 08/21/2023] Open
Abstract
With quantum computing devices increasing in scale and complexity, there is a growing need for tools that obtain precise diagnostic information about quantum operations. However, current quantum devices are only capable of short unstructured gate sequences followed by native measurements. We accept this limitation and turn it into a new paradigm for characterizing quantum gate-sets. A single experiment-random sequence estimation-solves a wealth of estimation problems, with all complexity moved to classical post-processing. We derive robust channel variants of shadow estimation with close-to-optimal performance guarantees and use these as a primitive for partial, compressive and full process tomography as well as the learning of Pauli noise. We discuss applications to the quantum gate engineering cycle, and propose novel methods for the optimization of quantum gates and diagnosing cross-talk.
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Affiliation(s)
- J Helsen
- QuSoft, Centrum Wiskunde & Informatica (CWI), Amsterdam, The Netherlands.
- Korteweg-de Vries Institute for Mathematics, University of Amsterdam, Amsterdam, The Netherlands.
| | - M Ioannou
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195, Berlin, Germany
| | - J Kitzinger
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195, Berlin, Germany
- Humboldt-Universität zu Berlin, Institut für Physik, 12489, Berlin, Germany
| | - E Onorati
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195, Berlin, Germany
- Department of Computer Science, University College London, London, UK
- Fakultät für Mathematik, Technische Universität München, München, Germany
| | - A H Werner
- Department of Mathematical Sciences, University of Copenhagen, 2100, København, Denmark
- NBIA, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, København, Denmark
| | - J Eisert
- Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195, Berlin, Germany.
- Helmholtz-Zentrum Berlin für Materialien und Energie, 14109, Berlin, Germany.
- Fraunhofer Heinrich Hertz Institute, 10587, Berlin, Germany.
| | - I Roth
- Quantum Research Center, Technology Innovation Institute (TII), Abu Dhabi, UAE.
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111
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Bermejo P, Orús R. Variational quantum and quantum-inspired clustering. Sci Rep 2023; 13:13284. [PMID: 37587176 PMCID: PMC10432530 DOI: 10.1038/s41598-023-39771-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/31/2023] [Indexed: 08/18/2023] Open
Abstract
Here we present a quantum algorithm for clustering data based on a variational quantum circuit. The algorithm allows to classify data into many clusters, and can easily be implemented in few-qubit Noisy Intermediate-Scale Quantum devices. The idea of the algorithm relies on reducing the clustering problem to an optimization, and then solving it via a Variational Quantum Eigensolver combined with non-orthogonal qubit states. In practice, the method uses maximally-orthogonal states of the target Hilbert space instead of the usual computational basis, allowing for a large number of clusters to be considered even with few qubits. We benchmark the algorithm with numerical simulations using real datasets, showing excellent performance even with one single qubit. Moreover, a tensor network simulation of the algorithm implements, by construction, a quantum-inspired clustering algorithm that can run on current classical hardware.
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Affiliation(s)
- Pablo Bermejo
- Multiverse Computing, Paseo de Miramón 170, 20014, San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastián, Spain
| | - Román Orús
- Multiverse Computing, Paseo de Miramón 170, 20014, San Sebastián, Spain.
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastián, Spain.
- Ikerbasque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao, Spain.
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112
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Diviánszky P, Márton I, Bene E, Vértesi T. Certification of qubits in the prepare-and-measure scenario with large input alphabet and connections with the Grothendieck constant. Sci Rep 2023; 13:13200. [PMID: 37580385 PMCID: PMC10425422 DOI: 10.1038/s41598-023-39529-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 07/26/2023] [Indexed: 08/16/2023] Open
Abstract
We address the problem of testing the quantumness of two-dimensional systems in the prepare-and-measure (PM) scenario, using a large number of preparations and a large number of measurement settings, with binary outcome measurements. In this scenario, we introduce constants, which we relate to the Grothendieck constant of order 3. We associate them with the white noise resistance of the prepared qubits and to the critical detection efficiency of the measurements performed. Large-scale numerical tools are used to bound the constants. This allows us to obtain new bounds on the minimum detection efficiency that a setup with 70 preparations and 70 measurement settings can tolerate.
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Affiliation(s)
- Péter Diviánszky
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - István Márton
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - Erika Bene
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary
| | - Tamás Vértesi
- MTA Atomki Lendület Quantum Correlations Research Group, Institute for Nuclear Research, P.O. Box 51, Debrecen, H-4001, Hungary.
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113
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Zhao J, Jeng H, Conlon LO, Tserkis S, Shajilal B, Liu K, Ralph TC, Assad SM, Lam PK. Enhancing quantum teleportation efficacy with noiseless linear amplification. Nat Commun 2023; 14:4745. [PMID: 37550329 PMCID: PMC10406873 DOI: 10.1038/s41467-023-40438-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 07/28/2023] [Indexed: 08/09/2023] Open
Abstract
Quantum teleportation constitutes a fundamental tool for various applications in quantum communication and computation. However, state-of-the-art continuous-variable quantum teleportation is restricted to moderate fidelities and short-distance configurations. This is due to unavoidable experimental imperfections resulting in thermal decoherence during the teleportation process. Here we present a heralded quantum teleporter able to overcome these limitations through noiseless linear amplification. As a result, we report a high fidelity of 92% for teleporting coherent states using a modest level of quantum entanglement. Our teleporter in principle allows nearly complete removal of loss induced onto the input states being transmitted through imperfect quantum channels. We further demonstrate the purification of a displaced thermal state, impossible via conventional deterministic amplification or teleportation approaches. The combination of high-fidelity coherent state teleportation alongside the purification of thermalized input states permits the transmission of quantum states over significantly long distances. These results are of both practical and fundamental significance; overcoming long-standing hurdles en route to highly-efficient continuous-variable quantum teleportation, while also shining new light on applying teleportation to purify quantum systems from thermal noise.
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Affiliation(s)
- Jie Zhao
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
- Joint Quantum Institute, National Institute of Standard and Technology and University of Maryland, College park, 20742, MD, USA
| | - Hao Jeng
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Lorcán O Conlon
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Spyros Tserkis
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Biveen Shajilal
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Kui Liu
- State key laboratory of quantum optics and quantum optics devices, Institute of Opto-Electronics, Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Timothy C Ralph
- Centre for Quantum Computation and Communication Technology, School of Mathematics and Physics, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Syed M Assad
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
| | - Ping Koy Lam
- Centre for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia.
- Institute of Materials Research and Engineering, Agency for Science Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore.
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114
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Kharoof A, Ipek S, Okay C. Topological Methods for Studying Contextuality: N-Cycle Scenarios and Beyond. Entropy (Basel) 2023; 25:1127. [PMID: 37628157 PMCID: PMC10453670 DOI: 10.3390/e25081127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 07/20/2023] [Indexed: 08/27/2023]
Abstract
Simplicial distributions are combinatorial models describing distributions on spaces of measurements and outcomes that generalize nonsignaling distributions on contextuality scenarios. This paper studies simplicial distributions on two-dimensional measurement spaces by introducing new topological methods. Two key ingredients are a geometric interpretation of Fourier-Motzkin elimination and a technique based on the collapsing of measurement spaces. Using the first one, we provide a new proof of Fine's theorem characterizing noncontextual distributions in N-cycle scenarios. Our approach goes beyond these scenarios and can describe noncontextual distributions in scenarios obtained by gluing cycle scenarios of various sizes. The second technique is used for detecting contextual vertices and deriving new Bell inequalities. Combined with these methods, we explore a monoid structure on simplicial distributions.
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Affiliation(s)
| | | | - Cihan Okay
- Mathematics Department, Bilkent University, Ankara 06800, Türkiye; (A.K.); (S.I.)
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115
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Bhattacharya U, Lamprou T, Maxwell AS, Ordonez A, Pisanty E, Rivera-Dean J, Stammer P, Ciappina MF, Lewenstein M, Tzallas P. Strong-laser-field physics, non-classical light states and quantum information science. Rep Prog Phys 2023. [PMID: 37489874 DOI: 10.1088/1361-6633/acea31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
Strong--laser--field physics is a research direction that relies on the use of high-power lasers and has led to fascinating achievements ranging from relativistic particle acceleration to attosecond science. On the other hand, quantum optics has been built on the use of low photon number sources and has opened the way for groundbreaking discoveries in quantum technology, advancing investigations ranging from fundamental tests of quantum theory to quantum information processing. Despite the tremendous progress, until recently these directions have remained disconnected. This is because, the majority of the interactions in the strong-field limit have been successfully described by semi-classical approximations treating the electromagnetic field classically, as there was no need to include the quantum properties of the field to explain the observations. The link between strong--laser--field physics, quantum optics, and quantum information science has been developed in the recent past. Studies based on fully quantized and conditioning approaches have shown that intense laser--matter interactions can be used for the generation of controllable entangled and non-classical light states. These achievements open the way for a vast number of investigations stemming from the symbiosis of strong--laser--field physics, quantum optics, and quantum information science. Here, after an introduction to the fundamentals of these research directions, we report on the recent progress in the fully quantized description of intense laser--matter interaction and the methods that have been developed for the generation of non-classical light states and entangled states. Also, we discuss the future directions of non-classical light engineering using strong laser fields, and the potential applications in ultrafast and quantum information science.
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Affiliation(s)
- Utso Bhattacharya
- ICFO-Institut de Ciencies Fotoniques, ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain, Castelldefels, Catalunya, 08860, SPAIN
| | - Theocharis Lamprou
- IESL, FORTH, N. Plastira 100, Vassilika Vouton GR-700 13, Heraklion (Crete), Greece, Heraklion (Crete), Crete, 71110, GREECE
| | - Andrew Stephen Maxwell
- Aarhus University Department of Physics and Astronomy, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark, Aarhus, Midtjylland, 8000, DENMARK
| | - Andres Ordonez
- ICFO, ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain, Castelldefels, Catalunya, 08860, SPAIN
| | - Emilio Pisanty
- Department of Physics, King's College London - Strand Campus, Strand Campus, Strand, London, WC2R 2LS, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Javier Rivera-Dean
- ICFO-Institut de Ciencies Fotoniques, ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain, Castelldefels, Catalunya, 08860, SPAIN
| | - Philipp Stammer
- Quantum Optics Theory, ICFO, Av. Carl Friedrich Gauss 3, Castelldefels, Castelldefels, 08860, SPAIN
| | - Marcelo F Ciappina
- Department of Physics, Guangdong Technion, Department of Physics, Guangdong Technion - Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong, China, 515063, Shantou, Guangdong, China, 515063, 515063, CHINA
| | - Maciej Lewenstein
- Quantum Optics Theory, Institut de Ciencies Fotoniques (ICFO), Carrer C.F. Gauss, 3, Parc Meditirani de la Tecnologia, Castelldefels, Barcelona, 08860, SPAIN
| | - Paraskevas Tzallas
- FORTH-IESL, Centre for Research and Technology Hellas, N. Plastira 100, Vassilika Vouton, Heraklion-Crete, Heraklion (Crete), 70013, GREECE
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116
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Katariya V, Bhusal N, You C. Experimental Guesswork with Quantum Side Information Using Twisted Light. Sensors (Basel) 2023; 23:6570. [PMID: 37514864 PMCID: PMC10383366 DOI: 10.3390/s23146570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023]
Abstract
Guesswork is an information-theoretic quantity which can be seen as an alternate security criterion to entropy. Recent work has established the theoretical framework for guesswork in the presence of quantum side information, which we extend both theoretically and experimentally. We consider guesswork when the side information consists of the BB84 states and their higher-dimensional generalizations. With this side information, we compute the guesswork for two different scenarios for each dimension. We then performed a proof-of-principle experiment using Laguerre-Gauss modes to experimentally compute the guesswork for higher-dimensional generalizations of the BB84 states. We find that our experimental results agree closely with our theoretical predictions. This work shows that guesswork can be a viable security criterion in cryptographic tasks and is experimentally accessible in a number of optical setups.
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Affiliation(s)
- Vishal Katariya
- Hearne Institute for Theoretical Physics, Department of Physics & Astronomy, and Center for Computation & Technology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Narayan Bhusal
- Quantum Photonics Laboratory, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Chenglong You
- Quantum Photonics Laboratory, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
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117
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Kim SK, Lee Y. The Necessary and Sufficient Conditions When Global and Local Fidelities Are Equal. Entropy (Basel) 2023; 25:1093. [PMID: 37510041 PMCID: PMC10378580 DOI: 10.3390/e25071093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/03/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023]
Abstract
In the field of quantum information theory, the concept of quantum fidelity is employed to quantify the similarity between two quantum states. It has been observed that the fidelity between two states describing a bipartite quantum system A⊗B is always less than or equal to the quantum fidelity between the states in subsystem A alone. While this fidelity inequality is well understood, determining the conditions under which the inequality becomes an equality remains an open question. In this paper, we present the necessary and sufficient conditions for the equality of fidelities between a bipartite system A⊗B and subsystem A, considering pure quantum states. Moreover, we provide explicit representations of quantum states that satisfy the fidelity equality, based on our derived results.
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Affiliation(s)
- Seong-Kun Kim
- Department of Liberal Studies, Kangwon National University, Samcheok 25913, Republic of Korea
| | - Yonghae Lee
- Department of Liberal Studies, Kangwon National University, Samcheok 25913, Republic of Korea
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118
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Wang SP, Ridolfo A, Li T, Savasta S, Nori F, Nakamura Y, You JQ. Probing the symmetry breaking of a light-matter system by an ancillary qubit. Nat Commun 2023; 14:4397. [PMID: 37474535 PMCID: PMC10359332 DOI: 10.1038/s41467-023-40097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 07/11/2023] [Indexed: 07/22/2023] Open
Abstract
Hybrid quantum systems in the ultrastrong, and even more in the deep-strong, coupling regimes can exhibit exotic physical phenomena and promise new applications in quantum technologies. In these nonperturbative regimes, a qubit-resonator system has an entangled quantum vacuum with a nonzero average photon number in the resonator, where the photons are virtual and cannot be directly detected. The vacuum field, however, is able to induce the symmetry breaking of a dispersively coupled probe qubit. We experimentally observe the parity symmetry breaking of an ancillary Xmon artificial atom induced by the field of a lumped-element superconducting resonator deep-strongly coupled with a flux qubit. This result opens a way to experimentally explore the novel quantum-vacuum effects emerging in the deep-strong coupling regime.
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Affiliation(s)
- Shuai-Peng Wang
- Quantum Physics and Quantum Information Division, Beijing Computational Science Research Center, Beijing, 100193, China
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China
| | - Alessandro Ridolfo
- Dipartimento di Fisica e Astronomia, Università di Catania, 95123, Catania, Italy
| | - Tiefu Li
- School of Integrated Circuits, and Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
| | - Salvatore Savasta
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, I-98166, Messina, Italy.
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako, Saitama, 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, MI, 48109-1040, USA
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
| | - Y Nakamura
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
- Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - J Q You
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China.
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119
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Goss N, Morvan A, Marinelli B, Mitchell BK, Nguyen LB, Naik RK, Chen L, Jünger C, Kreikebaum JM, Santiago DI, Wallman JJ, Siddiqi I. Author Correction: High-fidelity qutrit entangling gates for superconducting circuits. Nat Commun 2023; 14:4256. [PMID: 37460551 PMCID: PMC10352233 DOI: 10.1038/s41467-023-40049-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023] Open
Affiliation(s)
- Noah Goss
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Alexis Morvan
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brian Marinelli
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Bradley K Mitchell
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Long B Nguyen
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ravi K Naik
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Larry Chen
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Christian Jünger
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - John Mark Kreikebaum
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - David I Santiago
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joel J Wallman
- Keysight Technologies Canada, Kanata, ON, K2K 2W5, Canada
| | - Irfan Siddiqi
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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120
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Schiansky P, Kalb J, Sztatecsny E, Roehsner MC, Guggemos T, Trenti A, Bozzio M, Walther P. Demonstration of quantum-digital payments. Nat Commun 2023; 14:3849. [PMID: 37386044 PMCID: PMC10310712 DOI: 10.1038/s41467-023-39519-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 06/15/2023] [Indexed: 07/01/2023] Open
Abstract
Digital payments have replaced physical banknotes in many aspects of our daily lives. Similarly to banknotes, they should be easy to use, unique, tamper-resistant and untraceable, but additionally withstand digital attackers and data breaches. Current technology substitutes customers' sensitive data by randomized tokens, and secures the payment's uniqueness with a cryptographic function, called a cryptogram. However, computationally powerful attacks violate the security of these functions. Quantum technology comes with the potential to protect even against infinite computational power. Here, we show how quantum light can secure daily digital payments by generating inherently unforgeable quantum cryptograms. We implement the scheme over an urban optical fiber link, and show its robustness to noise and loss-dependent attacks. Unlike previously proposed protocols, our solution does not depend on long-term quantum storage or trusted agents and authenticated channels. It is practical with near-term technology and may herald an era of quantum-enabled security.
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Affiliation(s)
- Peter Schiansky
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Julia Kalb
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Esther Sztatecsny
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Marie-Christine Roehsner
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
- Security and Communication Technologies, Center for Digital Safety and Security, AIT Austrian Institute of Technology GmbH, Giefinggasse 4, 1210, Vienna, Austria
| | - Tobias Guggemos
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
| | - Alessandro Trenti
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria
- Security and Communication Technologies, Center for Digital Safety and Security, AIT Austrian Institute of Technology GmbH, Giefinggasse 4, 1210, Vienna, Austria
| | - Mathieu Bozzio
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria.
| | - Philip Walther
- University of Vienna, Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), 1090, Vienna, Austria.
- Christian Doppler Laboratory for Photonic Quantum Computer, Faculty of Physics, University of Vienna, 1090, Vienna, Austria.
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121
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Pastushenko VA, Kronberg DA. Improving the Performance of Quantum Cryptography by Using the Encryption of the Error Correction Data. Entropy (Basel) 2023; 25:956. [PMID: 37372300 DOI: 10.3390/e25060956] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023]
Abstract
Security of quantum key distribution (QKD) protocols rely solely on quantum physics laws, namely, on the impossibility to distinguish between non-orthogonal quantum states with absolute certainty. Due to this, a potential eavesdropper cannot extract full information from the states stored in their quantum memory after an attack despite knowing all the information disclosed during classical post-processing stages of QKD. Here, we introduce the idea of encrypting classical communication related to error-correction in order to decrease the amount of information available to the eavesdropper and hence improve the performance of quantum key distribution protocols. We analyze the applicability of the method in the context of additional assumptions concerning the eavesdropper's quantum memory coherence time and discuss the similarity of our proposition and the quantum data locking (QDL) technique.
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122
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Gao J, Wang Y, Song Z, Wang S. Quantum Image Encryption Based on Quantum DNA Codec and Pixel-Level Scrambling. Entropy (Basel) 2023; 25:865. [PMID: 37372209 DOI: 10.3390/e25060865] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/14/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023]
Abstract
In order to increase the security and robustness of quantum images, this study combined the quantum DNA codec with quantum Hilbert scrambling to offer an enhanced quantum image encryption technique. Initially, to accomplish pixel-level diffusion and create enough key space for the picture, a quantum DNA codec was created to encode and decode the pixel color information of the quantum image using its special biological properties. Second, we used quantum Hilbert scrambling to muddle the image position data in order to double the encryption effect. In order to enhance the encryption effect, the altered picture was then employed as a key matrix in a quantum XOR operation with the original image. The inverse transformation of the encryption procedure may be used to decrypt the picture since all the quantum operations employed in this research are reversible. The two-dimensional optical image encryption technique presented in this study may significantly strengthen the anti-attack of quantum picture, according to experimental simulation and result analysis. The correlation chart demonstrates that the average information entropy of the RGB three channels is more than 7.999, the average NPCR and UACI are respectively 99.61% and 33.42%, and the peak value of the ciphertext picture histogram is uniform. It offers more security and robustness than earlier algorithms and can withstand statistical analysis and differential assaults.
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Affiliation(s)
- Jie Gao
- School of Information and Control Engineering, Qingdao University of Technology, Qingdao 266520, China
| | - Yinuo Wang
- School of Science, Qingdao University of Technology, Qingdao 266520, China
| | - Zhaoyang Song
- School of Information and Control Engineering, Qingdao University of Technology, Qingdao 266520, China
| | - Shumei Wang
- School of Science, Qingdao University of Technology, Qingdao 266520, China
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123
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Akram J, Zheng C. Theoretical investigation of dynamics and concurrence of entangled [Formula: see text] and anti-[Formula: see text] symmetric polarized photons. Sci Rep 2023; 13:8542. [PMID: 37236997 PMCID: PMC10220064 DOI: 10.1038/s41598-023-34516-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023] Open
Abstract
Non-Hermitian systems with parity-time [Formula: see text] symmetry and anti-parity-time [Formula: see text] symmetry have exceptional points (EPs) resulting from eigenvector co-coalescence with exceptional properties. In the quantum and classical domains, higher-order EPs for [Formula: see text] symmetry and [Formula: see text]-symmetry systems have been proposed and realized. Both two-qubits [Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text] symmetric systems have seen an increase in recent years, especially in the dynamics of quantum entanglement. However, to our knowledge, neither theoretical nor experimental investigations have been conducted for the dynamics of two-qubits entanglement in the [Formula: see text]-[Formula: see text] symmetric system. We investigate the [Formula: see text]-[Formula: see text] dynamics for the first time. Moreover, we examine the impact of different initial Bell-state conditions on entanglement dynamics in [Formula: see text]-[Formula: see text], [Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text] symmetric systems. Additionally, we conduct a comparative study of entanglement dynamics in the [Formula: see text]-[Formula: see text] symmetrical system, [Formula: see text]-[Formula: see text] symmetrical system, and [Formula: see text]-[Formula: see text] symmetrical systems in order to learn more about non-Hermitian quantum systems and their environments. Entangled qubits evolve in a [Formula: see text]-[Formula: see text] symmetric unbroken regime, the entanglement oscillates with two different oscillation frequencies, and the entanglement is well preserved for a long period of time for the case when non-Hermitian parts of both qubits are taken quite away from the exceptional points.
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Affiliation(s)
- Javed Akram
- eleQtron GmbH, Martinshardt 19, 57074 Siegen, Germany
- Department of Physics, COMSATS University Islamabad, Islamabad, 45550 Pakistan
| | - Chao Zheng
- Department of Physics, College of Science, North China University of Technology, Beijing, 100144 China
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124
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Gallus C, Blasiak P, Pothos EM. Winning a CHSH Game without Entangled Particles in a Finite Number of Biased Rounds: How Much Luck Is Needed? Entropy (Basel) 2023; 25:e25050824. [PMID: 37238579 DOI: 10.3390/e25050824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/15/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023]
Abstract
Quantum games, such as the CHSH game, are used to illustrate the puzzle and power of entanglement. These games are played over many rounds and in each round, the participants, Alice and Bob, each receive a question bit to which they each have to give an answer bit, without being able to communicate during the game. When all possible classical answering strategies are analyzed, it is found that Alice and Bob cannot win more than 75% of the rounds. A higher percentage of wins arguably requires an exploitable bias in the random generation of the question bits or access to "non-local" resources, such as entangled pairs of particles. However, in an actual game, the number of rounds has to be finite and question regimes may come up with unequal likelihood, so there is always a possibility that Alice and Bob win by pure luck. This statistical possibility has to be transparently analyzed for practical applications such as the detection of eavesdropping in quantum communication. Similarly, when Bell tests are used in macroscopic situations to investigate the connection strength between system components and the validity of proposed causal models, the available data are limited and the possible combinations of question bits (measurement settings) may not be controlled to occur with equal likelihood. In the present work, we give a fully self-contained proof for a bound on the probability to win a CHSH game by pure luck without making the usual assumption of only small biases in the random number generators. We also show bounds for the case of unequal probabilities based on results from McDiarmid and Combes and numerically illustrate certain exploitable biases.
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Affiliation(s)
- Christoph Gallus
- THM Business School, Technische Hochschule Mittelhessen, D-35390 Gießen, Germany
| | - Pawel Blasiak
- Institute for Quantum Studies, Chapman University, Orange, CA 92866, USA
- Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków, Poland
| | - Emmanuel M Pothos
- Psychology Department, City, University of London, London EC1V 0HB, UK
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125
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Ray S, Alsing PM, Cafaro C, Jacinto HS. A Differential-Geometric Approach to Quantum Ignorance Consistent with Entropic Properties of Statistical Mechanics. Entropy (Basel) 2023; 25:e25050788. [PMID: 37238543 DOI: 10.3390/e25050788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/03/2023] [Accepted: 05/07/2023] [Indexed: 05/28/2023]
Abstract
In this paper, we construct the metric tensor and volume for the manifold of purifications associated with an arbitrary reduced density operator ρS. We also define a quantum coarse-graining (CG) to study the volume where macrostates are the manifolds of purifications, which we call surfaces of ignorance (SOI), and microstates are the purifications of ρS. In this context, the volume functions as a multiplicity of the macrostates that quantifies the amount of information missing from ρS. Using examples where the SOI are generated using representations of SU(2), SO(3), and SO(N), we show two features of the CG: (1) A system beginning in an atypical macrostate of smaller volume evolves to macrostates of greater volume until it reaches the equilibrium macrostate in a process in which the system and environment become strictly more entangled, and (2) the equilibrium macrostate takes up the vast majority of the coarse-grained space especially as the dimension of the total system becomes large. Here, the equilibrium macrostate corresponds to a maximum entanglement between the system and the environment. To demonstrate feature (1) for the examples considered, we show that the volume behaves like the von Neumann entropy in that it is zero for pure states, maximal for maximally mixed states, and is a concave function with respect to the purity of ρS. These two features are essential to typicality arguments regarding thermalization and Boltzmann's original CG.
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Affiliation(s)
- Shannon Ray
- Air Force Research Laboratory, Rome, NY 13441, USA
- Griffiss Institute, Rome, NY 13441, USA
| | | | - Carlo Cafaro
- Department of Mathematics and Physics, SUNY Polytechnic Institute, Albany, NY 12203, USA
| | - H S Jacinto
- Air Force Research Laboratory, Rome, NY 13441, USA
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126
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Hrmo P, Wilhelm B, Gerster L, van Mourik MW, Huber M, Blatt R, Schindler P, Monz T, Ringbauer M. Native qudit entanglement in a trapped ion quantum processor. Nat Commun 2023; 14:2242. [PMID: 37076475 PMCID: PMC10115791 DOI: 10.1038/s41467-023-37375-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/15/2023] [Indexed: 04/21/2023] Open
Abstract
Quantum information carriers, just like most physical systems, naturally occupy high-dimensional Hilbert spaces. Instead of restricting them to a two-level subspace, these high-dimensional (qudit) quantum systems are emerging as a powerful resource for the next generation of quantum processors. Yet harnessing the potential of these systems requires efficient ways of generating the desired interaction between them. Here, we experimentally demonstrate an implementation of a native two-qudit entangling gate up to dimension 5 in a trapped-ion system. This is achieved by generalizing a recently proposed light-shift gate mechanism to generate genuine qudit entanglement in a single application of the gate. The gate seamlessly adapts to the local dimension of the system with a calibration overhead that is independent of the dimension.
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Affiliation(s)
- Pavel Hrmo
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria.
| | - Benjamin Wilhelm
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
| | - Lukas Gerster
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
| | - Martin W van Mourik
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
| | - Marcus Huber
- Atominstitut, Technische Universität Wien, 1020, Vienna, Austria
- Institute for Quantum Optics and Quantum Information-IQOQI Vienna, Austrian Academy of Sciences, Boltzmanngasse 3, 1090, Vienna, Austria
| | - Rainer Blatt
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020, Innsbruck, Austria
- AQT, Technikerstraße 17, 6020, Innsbruck, Austria
| | - Philipp Schindler
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
| | - Thomas Monz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
- AQT, Technikerstraße 17, 6020, Innsbruck, Austria
| | - Martin Ringbauer
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25/4, 6020, Innsbruck, Austria
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127
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Perminov NS, Moiseev SA. Integrated Multiresonator Quantum Memory. Entropy (Basel) 2023; 25:e25040623. [PMID: 37190411 PMCID: PMC10138295 DOI: 10.3390/e25040623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/28/2023] [Accepted: 04/01/2023] [Indexed: 05/17/2023]
Abstract
We develop an integrated efficient multiresonator quantum memory scheme based on a system of three interacting resonators coupled through a common resonator to an external waveguide via switchable coupler. It is shown that high-precision parameter matching based on step-by-step optimization makes it possible to efficiently store the signal field and enables on-demand retrieval of the signal at specified time moments. Possible experimental implementations and practical applications of the proposed quantum memory scheme are discussed.
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Affiliation(s)
- Nikolay Sergeevich Perminov
- Kazan Quantum Center, Kazan National Research Technical University, n.a. A.N.Tupolev-KAI, 10 K. Marx, 420111 Kazan, Russia
- Zavoisky Physical-Technical Institute, Kazan Scientific Center of the Russian Academy of Sciences, 10/7 Sibirsky Tract, 420029 Kazan, Russia
| | - Sergey Andreevich Moiseev
- Kazan Quantum Center, Kazan National Research Technical University, n.a. A.N.Tupolev-KAI, 10 K. Marx, 420111 Kazan, Russia
- Zavoisky Physical-Technical Institute, Kazan Scientific Center of the Russian Academy of Sciences, 10/7 Sibirsky Tract, 420029 Kazan, Russia
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128
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Ni Z, Li S, Deng X, Cai Y, Zhang L, Wang W, Yang ZB, Yu H, Yan F, Liu S, Zou CL, Sun L, Zheng SB, Xu Y, Yu D. Beating the break-even point with a discrete-variable-encoded logical qubit. Nature 2023; 616:56-60. [PMID: 36949191 PMCID: PMC10076216 DOI: 10.1038/s41586-023-05784-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/02/2023] [Indexed: 03/24/2023]
Abstract
Quantum error correction (QEC) aims to protect logical qubits from noises by using the redundancy of a large Hilbert space, which allows errors to be detected and corrected in real time1. In most QEC codes2-8, a logical qubit is encoded in some discrete variables, for example photon numbers, so that the encoded quantum information can be unambiguously extracted after processing. Over the past decade, repetitive QEC has been demonstrated with various discrete-variable-encoded scenarios9-17. However, extending the lifetimes of thus-encoded logical qubits beyond the best available physical qubit still remains elusive, which represents a break-even point for judging the practical usefulness of QEC. Here we demonstrate a QEC procedure in a circuit quantum electrodynamics architecture18, where the logical qubit is binomially encoded in photon-number states of a microwave cavity8, dispersively coupled to an auxiliary superconducting qubit. By applying a pulse featuring a tailored frequency comb to the auxiliary qubit, we can repetitively extract the error syndrome with high fidelity and perform error correction with feedback control accordingly, thereby exceeding the break-even point by about 16% lifetime enhancement. Our work illustrates the potential of hardware-efficient discrete-variable encodings for fault-tolerant quantum computation19.
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Affiliation(s)
- Zhongchu Ni
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Department of Physics, Southern University of Science and Technology, Shenzhen, China
| | - Sai Li
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Xiaowei Deng
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Yanyan Cai
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Libo Zhang
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Weiting Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Zhen-Biao Yang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, China
| | - Haifeng Yu
- Beijing Academy of Quantum Information Sciences, Beijing, China
| | - Fei Yan
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Song Liu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- International Quantum Academy, and Shenzhen Branch, Hefei National Laboratory, Shenzhen, China
| | - Chang-Ling Zou
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory, Hefei, China
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China.
- Hefei National Laboratory, Hefei, China.
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, China.
| | - Yuan Xu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
- International Quantum Academy, and Shenzhen Branch, Hefei National Laboratory, Shenzhen, China.
| | - Dapeng Yu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
- Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
- Department of Physics, Southern University of Science and Technology, Shenzhen, China.
- International Quantum Academy, and Shenzhen Branch, Hefei National Laboratory, Shenzhen, China.
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129
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Guala D, Zhang S, Cruz E, Riofrío CA, Klepsch J, Arrazola JM. Practical overview of image classification with tensor-network quantum circuits. Sci Rep 2023; 13:4427. [PMID: 36932074 DOI: 10.1038/s41598-023-30258-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/20/2023] [Indexed: 03/19/2023] Open
Abstract
Circuit design for quantum machine learning remains a formidable challenge. Inspired by the applications of tensor networks across different fields and their novel presence in the classical machine learning context, one proposed method to design variational circuits is to base the circuit architecture on tensor networks. Here, we comprehensively describe tensor-network quantum circuits and how to implement them in simulations. This includes leveraging circuit cutting, a technique used to evaluate circuits with more qubits than those available on current quantum devices. We then illustrate the computational requirements and possible applications by simulating various tensor-network quantum circuits with PennyLane, an open-source python library for differential programming of quantum computers. Finally, we demonstrate how to apply these circuits to increasingly complex image processing tasks, completing this overview of a flexible method to design circuits that can be applied to industrially-relevant machine learning tasks.
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130
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Qian K, Wang K, Chen L, Hou Z, Krenn M, Zhu S, Ma XS. Multiphoton non-local quantum interference controlled by an undetected photon. Nat Commun 2023; 14:1480. [PMID: 36932077 PMCID: PMC10023773 DOI: 10.1038/s41467-023-37228-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 03/08/2023] [Indexed: 03/18/2023] Open
Abstract
The interference of quanta lies at the heart of quantum physics. The multipartite generalization of single-quanta interference creates entanglement, the coherent superposition of states shared by several quanta. Entanglement allows non-local correlations between many quanta and hence is a key resource for quantum information technology. Entanglement is typically considered to be essential for creating non-local quantum interference. Here, we show that this is not the case and demonstrate multiphoton non-local quantum interference that does not require entanglement of any intrinsic properties of the photons. We harness the superposition of the physical origin of a four-photon product state, which leads to constructive and destructive interference with the photons' mere existence. With the intrinsic indistinguishability in the generation process of photons, we realize four-photon frustrated quantum interference. This allows us to observe the following noteworthy difference to quantum entanglement: We control the non-local multipartite quantum interference with a photon that we never detect, which does not require quantum entanglement. These non-local properties pave the way for the studies of foundations of quantum physics and potential applications in quantum technologies.
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Affiliation(s)
- Kaiyi Qian
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Kai Wang
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Leizhen Chen
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Zhaohua Hou
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Mario Krenn
- Max Planck Institute for the Science of Light (MPL), Erlangen, Germany.
| | - Shining Zhu
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Xiao-Song Ma
- National Laboratory of Solid-state Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China. .,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui, 230026, China. .,Hefei National Laboratory, Hefei, 230088, China.
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131
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Wechs J, Branciard C, Oreshkov O. Existence of processes violating causal inequalities on time-delocalised subsystems. Nat Commun 2023; 14:1471. [PMID: 36928637 PMCID: PMC10020554 DOI: 10.1038/s41467-023-36893-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 02/22/2023] [Indexed: 03/18/2023] Open
Abstract
It has been shown that it is theoretically possible for there to exist quantum and classical processes in which the operations performed by separate parties do not occur in a well-defined causal order. A central question is whether and how such processes can be realised in practice. In order to provide a rigorous framework for the notion that certain such processes have a realisation in standard quantum theory, the concept of time-delocalised quantum subsystem has been introduced. In this paper, we show that realisations on time-delocalised subsystems exist for all unitary extensions of tripartite processes. This class contains processes that violate causal inequalities, i.e., that can generate correlations that witness the incompatibility with definite causal order in a device-independent manner, and whose realisability has been a central open problem. We consider a known example of such a tripartite classical process that has a unitary extension, and study its realisation on time-delocalised subsystems. We then discuss this finding with regard to the assumptions that underlie causal inequalities, and argue that they are indeed a meaningful concept to show the absence of a definite causal order between the variables of interest.
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Affiliation(s)
- Julian Wechs
- QuIC, Ecole Polytechnique de Bruxelles, C.P. 165, Université Libre de Bruxelles, 1050, Brussels, Belgium. .,Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France.
| | - Cyril Branciard
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France.
| | - Ognyan Oreshkov
- QuIC, Ecole Polytechnique de Bruxelles, C.P. 165, Université Libre de Bruxelles, 1050, Brussels, Belgium.
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132
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Moskalev DO, Zikiy EV, Pishchimova AA, Ezenkova DA, Smirnov NS, Ivanov AI, Korshakov ND, Rodionov IA. Optimization of shadow evaporation and oxidation for reproducible quantum Josephson junction circuits. Sci Rep 2023; 13:4174. [PMID: 36914735 DOI: 10.1038/s41598-023-31003-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/06/2023] [Indexed: 03/14/2023] Open
Abstract
The most commonly used physical realization of superconducting qubits for quantum circuits is a transmon. There are a number of superconducting quantum circuits applications, where Josephson junction critical current reproducibility over a chip is crucial. Here, we report on a robust chip scale Al/AlOx/Al junctions fabrication method due to comprehensive study of shadow evaporation and oxidation steps. We experimentally demonstrate the evidence of optimal Josephson junction electrodes thickness, deposition rate and deposition angle, which ensure minimal electrode surface and line edge roughness. The influence of oxidation method, pressure and time on critical current reproducibility is determined. With the proposed method we demonstrate Al/AlOx/Al junction fabrication with the critical current variation [Formula: see text] less than 3.9% (from 150 × 200 to 150 × 600 nm2 area) and 7.7% (for 100 × 100 nm2 area) over 20 × 20 mm2 chip. Finally, we fabricate separately three 5 × 10 mm2 chips with 18 transmon qubits (near 4.3 GHz frequency) showing less than 1.9% frequency variation between qubits on different chips. The proposed approach and optimization criteria can be utilized for a robust wafer-scale superconducting qubit circuits fabrication.
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133
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Haque ME, Paul M, Ulhaq A, Debnath T. Advanced quantum image representation and compression using a DCT-EFRQI approach. Sci Rep 2023; 13:4129. [PMID: 36914672 PMCID: PMC10011390 DOI: 10.1038/s41598-023-30575-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
In recent years, quantum image computing draws a lot of attention due to storing and processing image data faster compared to classical computers. A number of approaches have been proposed to represent the quantum image inside a quantum computer. Representing and compressing medium and big-size images inside the quantum computer is still challenging. To address this issue, we have proposed a block-wise DCT-EFRQI (Direct Cosine Transform Efficient Flexible Representation of Quantum Image) approach to represent and compress the gray-scale image efficiently to save computational time and reduce the quantum bits (qubits) for the state preparation. In this work, we have demonstrated the capability of block-wise DCT and DWT transformation inside the quantum domain to investigate their relative performances. The Quirk simulation tool is used to design the corresponding quantum image circuit. In the proposed DCT-EFRQI approach, a total of 17 qubits are used to represent the coefficients, the connection between coefficients and state (i.e., auxiliary), and their position for representing and compressing grayscale images inside a quantum computer. Among those, 8 qubits are used to map the coefficient values and the rest are used to generate the corresponding coefficient XY-coordinate position including one auxiliary qubit. Theoretical analysis and experimental results show that the proposed DCT-EFRQI scheme provides better representation and compression compared to DCT-GQIR, DWT-GQIR, and DWT-EFRQI in terms of rate-distortion performance.
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Affiliation(s)
- Md Ershadul Haque
- School of Computing Mathematics and Engineering, Charles Sturt University, Bathurst, NSW, 2795, Australia.
| | - Manoranjan Paul
- School of Computing Mathematics and Engineering, Charles Sturt University, Bathurst, NSW, 2795, Australia
| | - Anwaar Ulhaq
- School of Computing Mathematics and Engineering, Charles Sturt University, Bathurst, NSW, 2795, Australia
| | - Tanmoy Debnath
- School of Computing Mathematics and Engineering, Charles Sturt University, Bathurst, NSW, 2795, Australia
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134
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Podoshvedov MS, Podoshvedov SA, Kulik SP. Algorithm of quantum engineering of large-amplitude high-fidelity Schrödinger cat states. Sci Rep 2023; 13:3965. [PMID: 36894587 PMCID: PMC9998893 DOI: 10.1038/s41598-023-30218-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 02/17/2023] [Indexed: 03/11/2023] Open
Abstract
We present an algorithm of quantum engineering of large-amplitude [Formula: see text] high-fidelity [Formula: see text] even/odd Schrödinger cat states (SCSs) using a single mode squeezed vacuum (SMSV) state as resource. Set of [Formula: see text] beam splitters (BSs) with arbitrary transmittance and reflectance coefficients sequentially following each other acts as a hub that redirects a multiphoton state into the measuring modes simultaneously measured by photon number resolving (PNR) detectors. We show that the multiphoton state splitting guarantees significant increase of the success probability of the SCSs generator compared to its implementation in a single PNR detector version and imposes less requirements on ideal PNR detectors. We prove that the fidelity of the output SCSs and its success probability are in conflict with each other (which can be quantified) in a scheme with ineffective PNR detectors, especially when subtracting large (say, [Formula: see text]) number of photons, i.e., increasing the fidelity to perfect values leads to a sharp decrease in the success probability. In general, the strategy of subtracting up to [Formula: see text] photons from initial SMSV in setup with two BSs is acceptable for achieving sufficiently high values of the fidelity and success probability at the output of the generator of the SCSs of amplitude [Formula: see text] with two inefficient PNR detectors.
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Affiliation(s)
- Mikhail S Podoshvedov
- Laboratory of Quantum Engineering of Light, South Ural State University (SUSU), Chelyabinsk, Russia.,Institute of Physics, Kazan Federal University (KFU), Kazan, Russia
| | - Sergey A Podoshvedov
- Laboratory of Quantum Engineering of Light, South Ural State University (SUSU), Chelyabinsk, Russia.
| | - Sergei P Kulik
- Laboratory of Quantum Engineering of Light, South Ural State University (SUSU), Chelyabinsk, Russia.,Quantum Technology Centre, M.V. Lomonosov Moscow State University, Moscow, Russia
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135
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Chen XD, Wang EH, Shan LK, Zhang SC, Feng C, Zheng Y, Dong Y, Guo GC, Sun FW. Quantum enhanced radio detection and ranging with solid spins. Nat Commun 2023; 14:1288. [PMID: 36894541 PMCID: PMC9998632 DOI: 10.1038/s41467-023-36929-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/21/2023] [Indexed: 03/11/2023] Open
Abstract
The accurate radio frequency (RF) ranging and localizing of objects has benefited the researches including autonomous driving, the Internet of Things, and manufacturing. Quantum receivers have been proposed to detect the radio signal with ability that can outperform conventional measurement. As one of the most promising candidates, solid spin shows superior robustness, high spatial resolution and miniaturization. However, challenges arise from the moderate response to a high frequency RF signal. Here, by exploiting the coherent interaction between quantum sensor and RF field, we demonstrate quantum enhanced radio detection and ranging. The RF magnetic sensitivity is improved by three orders to 21 [Formula: see text], based on nanoscale quantum sensing and RF focusing. Further enhancing the response of spins to the target's position through multi-photon excitation, a ranging accuracy of 16 μm is realized with a GHz RF signal. The results pave the way for exploring quantum enhanced radar and communications with solid spins.
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Affiliation(s)
- Xiang-Dong Chen
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China.,Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, P. R. China
| | - En-Hui Wang
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Long-Kun Shan
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Shao-Chun Zhang
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Ce Feng
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Yu Zheng
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Yang Dong
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Guang-Can Guo
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China.,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China.,Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, P. R. China
| | - Fang-Wen Sun
- CAS Key Laboratory of Quantum Information, School of Physical Sciences, University of Science and Technology of China, Hefei, 230026, P. R. China. .,CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, P. R. China. .,Hefei National Laboratory, University of Science and Technology of China, Hefei, 230088, P. R. China.
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136
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Aboussalah AM, Chi C, Lee CG. Quantum computing reduces systemic risk in financial networks. Sci Rep 2023; 13:3990. [PMID: 36894579 DOI: 10.1038/s41598-023-30710-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/28/2023] [Indexed: 03/11/2023] Open
Abstract
In highly connected financial networks, the failure of a single institution can cascade into additional bank failures. This systemic risk can be mitigated by adjusting the loans, holding shares, and other liabilities connecting institutions in a way that prevents cascading of failures. We are approaching the systemic risk problem by attempting to optimize the connections between the institutions. In order to provide a more realistic simulation environment, we have incorporated nonlinear/discontinuous losses in the value of the banks. To address scalability challenges, we have developed a two-stage algorithm where the networks are partitioned into modules of highly interconnected banks and then the modules are individually optimized. We developed a new algorithms for classical and quantum partitioning for directed and weighed graphs (first stage) and a new methodology for solving Mixed Integer Linear Programming problems with constraints for the systemic risk context (second stage). We compare classical and quantum algorithms for the partitioning problem. Experimental results demonstrate that our two-stage optimization with quantum partitioning is more resilient to financial shocks, delays the cascade failure phase transition, and reduces the total number of failures at convergence under systemic risks with reduced time complexity.
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137
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Sannia A, Giordano A, Gullo NL, Mastroianni C, Plastina F. A hybrid classical-quantum approach to speed-up Q-learning. Sci Rep 2023; 13:3913. [PMID: 36890198 PMCID: PMC9995512 DOI: 10.1038/s41598-023-30990-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
We introduce a classical-quantum hybrid approach to computation, allowing for a quadratic performance improvement in the decision process of a learning agent. Using the paradigm of quantum accelerators, we introduce a routine that runs on a quantum computer, which allows for the encoding of probability distributions. This quantum routine is then employed, in a reinforcement learning set-up, to encode the distributions that drive action choices. Our routine is well-suited in the case of a large, although finite, number of actions and can be employed in any scenario where a probability distribution with a large support is needed. We describe the routine and assess its performance in terms of computational complexity, needed quantum resource, and accuracy. Finally, we design an algorithm showing how to exploit it in the context of Q-learning.
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Affiliation(s)
- A Sannia
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende, (CS), Italy.,Institute for Cross-Disciplinary Physics and Complex Systems (IFISC) UIB-CSIC, Campus Universitat Illes Balears, 07122, Palma de Mallorca, Spain
| | | | - N Lo Gullo
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende, (CS), Italy.,INFN, gruppo collegato di Cosenza, Cosenza, Italy.,Quantum Algorithms and Software, VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | | | - F Plastina
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende, (CS), Italy. .,INFN, gruppo collegato di Cosenza, Cosenza, Italy.
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138
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Shaib A, Naim MH, Fouda ME, Kanj R, Kurdahi F. Efficient noise mitigation technique for quantum computing. Sci Rep 2023; 13:3912. [PMID: 36890156 DOI: 10.1038/s41598-023-30510-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 02/24/2023] [Indexed: 03/10/2023] Open
Abstract
Quantum computers have enabled solving problems beyond the current machines' capabilities. However, this requires handling noise arising from unwanted interactions in these systems. Several protocols have been proposed to address efficient and accurate quantum noise profiling and mitigation. In this work, we propose a novel protocol that efficiently estimates the average output of a noisy quantum device to be used for quantum noise mitigation. The multi-qubit system average behavior is approximated as a special form of a Pauli Channel where Clifford gates are used to estimate the average output for circuits of different depths. The characterized Pauli channel error rates, and state preparation and measurement errors are then used to construct the outputs for different depths thereby eliminating the need for large simulations and enabling efficient mitigation. We demonstrate the efficiency of the proposed protocol on four IBM Q 5-qubit quantum devices. Our method demonstrates improved accuracy with efficient noise characterization. We report up to 88% and 69% improvement for the proposed approach compared to the unmitigated, and pure measurement error mitigation approaches, respectively.
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139
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Yoon CS, Hong CH, Kang MS, Choi JW, Yang HJ. Quantum asymmetric key crypto scheme using Grover iteration. Sci Rep 2023; 13:3810. [PMID: 36882516 PMCID: PMC9992374 DOI: 10.1038/s41598-023-30860-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 03/02/2023] [Indexed: 03/09/2023] Open
Abstract
Here, we propose a quantum asymmetric key cryptography scheme using Grover's quantum search algorithm. In the proposed scheme, Alice generates a pair of public and private keys, keeps the private keys safe, and only discloses public keys to the outside. Bob uses Alice's public key to send a secret message to Alice and Alice uses her private key to decrypt the secret message. Furthermore, we discuss the safety of quantum asymmetric key encryption techniques based on quantum mechanical properties.
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Affiliation(s)
- Chun Seok Yoon
- Department of Physics, Korea University, Sejong, 30019, South Korea
- Institute of Convergence Technology KT R&D Center, 151 Taebong-Ro, Seoul, 06763, Republic of Korea
| | - Chang Ho Hong
- The Affiliated Institute of Electronics and Telecommunications Research Institute, P.O. Box 1, Yuseong, Daejeon, 34188, Republic of Korea
| | - Min Sung Kang
- Korean Intellectual Property Office (KIPO), Government Complex Daejeon Building 4, 189, Cheongsa-Ro, Seogu, Daejeon, 35208, Republic of Korea
| | - Ji-Woong Choi
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Hyung Jin Yang
- Department of Physics, Korea University, Sejong, 30019, South Korea.
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140
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Li WC, Xiao Y, Han XH, Fan X, Hei XB, Gu YJ. Dynamics of multipartite quantum steering for different types of decoherence channels. Sci Rep 2023; 13:3798. [PMID: 36882469 DOI: 10.1038/s41598-023-30869-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 03/02/2023] [Indexed: 03/09/2023] Open
Abstract
Multipartite quantum steering, a unique resource for asymmetric quantum network information tasks, is very fragile to the inevitable decoherence, which makes it useless for practical purposes. It is thus of importance to understand how it decays in the presence of noise channels. We study the dynamic behaviors of genuine tripartite steering, reduced bipartite steering, and collective steering of a generalized three-qubit W state when only one qubit interacts independently with the amplitude damping channel (ADC), phase damping channel (PDC) or depolarizing channel (DC). Our results provide the region of decoherence strength and state parameters that each type of steering can survive. The results show that these steering correlations decay the slowest in PDC and some non-maximally entangled states more robust than the maximally entangled ones. Unlike entanglement and Bell nonlocality, the thresholds of decoherence strength that reduced bipartite steering and collective steering can survive depend on the steering direction. In addition, we find that not only one party can be steered by a group system, but also two parties can be steered by a single system. There is a trade-off between the monogamy relation involving one steered party and two steered parties. Our work provides comprehensive information about the effect of decoherence on multipartite quantum steering, which will help to realize quantum information processing tasks in the presence of noise environments.
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141
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Weinstein AJ, Reed MD, Jones AM, Andrews RW, Barnes D, Blumoff JZ, Euliss LE, Eng K, Fong BH, Ha SD, Hulbert DR, Jackson CAC, Jura M, Keating TE, Kerckhoff J, Kiselev AA, Matten J, Sabbir G, Smith A, Wright J, Rakher MT, Ladd TD, Borselli MG. Universal logic with encoded spin qubits in silicon. Nature 2023; 615:817-822. [PMID: 36746190 PMCID: PMC10060158 DOI: 10.1038/s41586-023-05777-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 01/31/2023] [Indexed: 02/08/2023]
Abstract
Quantum computation features known examples of hardware acceleration for certain problems, but is challenging to realize because of its susceptibility to small errors from noise or imperfect control. The principles of fault tolerance may enable computational acceleration with imperfect hardware, but they place strict requirements on the character and correlation of errors1. For many qubit technologies2-21, some challenges to achieving fault tolerance can be traced to correlated errors arising from the need to control qubits by injecting microwave energy matching qubit resonances. Here we demonstrate an alternative approach to quantum computation that uses energy-degenerate encoded qubit states controlled by nearest-neighbour contact interactions that partially swap the spin states of electrons with those of their neighbours. Calibrated sequences of such partial swaps, implemented using only voltage pulses, allow universal quantum control while bypassing microwave-associated correlated error sources1,22-28. We use an array of six 28Si/SiGe quantum dots, built using a platform that is capable of extending in two dimensions following processes used in conventional microelectronics29. We quantify the operational fidelity of universal control of two encoded qubits using interleaved randomized benchmarking30, finding a fidelity of 96.3% ± 0.7% for encoded controlled NOT operations and 99.3% ± 0.5% for encoded SWAP. The quantum coherence offered by enriched silicon5-9,16,18,20,22,27,29,31-37, the all-electrical and low-crosstalk-control of partial swap operations1,22-28 and the configurable insensitivity of our encoding to certain error sources28,33,34,38 all combine to offer a strong pathway towards scalable fault tolerance and computational advantage.
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Affiliation(s)
| | | | | | | | | | | | | | - Kevin Eng
- HRL Laboratories, LLC, Malibu, CA, USA
| | | | - Sieu D Ha
- HRL Laboratories, LLC, Malibu, CA, USA
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142
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Park S, Park DK, Rhee JK. Variational quantum approximate support vector machine with inference transfer. Sci Rep 2023; 13:3288. [PMID: 36841841 DOI: 10.1038/s41598-023-29495-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 02/06/2023] [Indexed: 02/27/2023] Open
Abstract
A kernel-based quantum classifier is the most practical and influential quantum machine learning technique for the hyper-linear classification of complex data. We propose a Variational Quantum Approximate Support Vector Machine (VQASVM) algorithm that demonstrates empirical sub-quadratic run-time complexity with quantum operations feasible even in NISQ computers. We experimented our algorithm with toy example dataset on cloud-based NISQ machines as a proof of concept. We also numerically investigated its performance on the standard Iris flower and MNIST datasets to confirm the practicality and scalability.
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143
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Freeman D, Giannakis D, Mintz B, Ourmazd A, Slawinska J. Data assimilation in operator algebras. Proc Natl Acad Sci U S A 2023; 120:e2211115120. [PMID: 36800390 DOI: 10.1073/pnas.2211115120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
We develop an algebraic framework for sequential data assimilation of partially observed dynamical systems. In this framework, Bayesian data assimilation is embedded in a nonabelian operator algebra, which provides a representation of observables by multiplication operators and probability densities by density operators (quantum states). In the algebraic approach, the forecast step of data assimilation is represented by a quantum operation induced by the Koopman operator of the dynamical system. Moreover, the analysis step is described by a quantum effect, which generalizes the Bayesian observational update rule. Projecting this formulation to finite-dimensional matrix algebras leads to computational schemes that are i) automatically positivity-preserving and ii) amenable to consistent data-driven approximation using kernel methods for machine learning. Moreover, these methods are natural candidates for implementation on quantum computers. Applications to the Lorenz 96 multiscale system and the El Niño Southern Oscillation in a climate model show promising results in terms of forecast skill and uncertainty quantification.
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144
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Lewandowska P, Pawela Ł, Puchała Z. Strategies for single-shot discrimination of process matrices. Sci Rep 2023; 13:3046. [PMID: 36810761 DOI: 10.1038/s41598-023-30191-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 02/17/2023] [Indexed: 02/23/2023] Open
Abstract
The topic of causality has recently gained traction quantum information research. This work examines the problem of single-shot discrimination between process matrices which are an universal method defining a causal structure. We provide an exact expression for the optimal probability of correct distinction. In addition, we present an alternative way to achieve this expression by using the convex cone structure theory. We also express the discrimination task as semidefinite programming. Due to that, we have created the SDP calculating the distance between process matrices and we quantify it in terms of the trace norm. As a valuable by-product, the program finds an optimal realization of the discrimination task. We also find two classes of process matrices which can be distinguished perfectly. Our main result, however, is a consideration of the discrimination task for process matrices corresponding to quantum combs. We study which strategy, adaptive or non-signalling, should be used during the discrimination task. We proved that no matter which strategy you choose, the probability of distinguishing two process matrices being a quantum comb is the same.
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145
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Bala R, Asthana S, Ravishankar V. Combating errors in quantum communication: an integrated approach. Sci Rep 2023; 13:2979. [PMID: 36805530 DOI: 10.1038/s41598-023-30178-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Near-term quantum communication protocols suffer inevitably from channel noises, whose alleviation has been mostly attempted with resources such as multiparty entanglement or sophisticated experimental techniques. Generation of multiparty higher dimensional entanglement is not easy. This calls for exploring realistic solutions which are implementable with current devices. Motivated particularly by the difficulty in generation of multiparty entangled states, in this paper, we have investigated error-free information transfer with minimal requirements. For this, we have proposed a new information encoding scheme for communication purposes. The encoding scheme is based on the fact that most noisy channels leave some quantities invariant. Armed with this fact, we encode information in these invariants. These invariants are functions of expectation values of operators. This information passes through the noisy channel unchanged. Pertinently, this approach is not in conflict with other existing error correction schemes. In fact, we have shown how standard quantum error-correcting codes emerge if suitable restrictions are imposed on the choices of logical basis states. As applications, for illustration, we propose a quantum key distribution protocol and an error-immune information transfer protocol.
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146
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Abstract
Twin-field (TF) quantum key distribution (QKD) has rapidly risen as the most viable solution to long-distance secure fibre communication thanks to its fundamentally repeater-like rate-loss scaling. However, its implementation complexity, if not successfully addressed, could impede or even prevent its advance into real-world. To satisfy its requirement for twin-field coherence, all present setups adopted essentially a gigantic, resource-inefficient interferometer structure that lacks scalability that mature QKD systems provide with simplex quantum links. Here we introduce a technique that can stabilise an open channel without using a closed interferometer and has general applicability to phase-sensitive quantum communications. Using locally generated frequency combs to establish mutual coherence, we develop a simple and versatile TF-QKD setup that does not need service fibre and can operate over links of 100 km asymmetry. We confirm the setup's repeater-like behaviour and obtain a finite-size rate of 0.32 bit/s at a distance of 615.6 km.
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Affiliation(s)
- Lai Zhou
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Jinping Lin
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Yumang Jing
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China
| | - Zhiliang Yuan
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
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147
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Vesperini A, Bel-Hadj-Aissa G, Franzosi R. Entanglement and quantum correlation measures for quantum multipartite mixed states. Sci Rep 2023; 13:2852. [PMID: 36806198 PMCID: PMC9938213 DOI: 10.1038/s41598-023-29438-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 02/03/2023] [Indexed: 02/19/2023] Open
Abstract
Entanglement, and quantum correlation, are precious resources for quantum technologies implementation based on quantum information science, such as quantum communication, quantum computing, and quantum interferometry. Nevertheless, to our best knowledge, a directly or numerically computable measure for the entanglement of multipartite mixed states is still lacking. In this work, (i) we derive a measure of the degree of quantum correlation for mixed multipartite states. The latter possesses a closed-form expression valid in the general case unlike, to our best knowledge, all other known measures of quantum correlation. (ii) We further propose an entanglement measure, derived from this quantum correlation measure using a novel regularization procedure for the density matrix. Therefore, a comparison of the proposed measures, of quantum correlation and entanglement, allows one to distinguish between quantum correlation detached from entanglement and the one induced by entanglement and, hence, to identify separable but non-classical states. We have tested our quantum correlation and entanglement measures, on states well-known in literature: a general Bell diagonal state and the Werner states, which are easily tractable with our regularization procedure, and we have verified the accordance between our measures and the expected results for these states. Finally, we validate the two measures in two cases of multipartite states. The first is a generalization to three qubits of the Werner state, the second is a one-parameter three qubits mixed state interpolating between a bi-separable state and a genuine multipartite state, passing through a fully separable state.
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Affiliation(s)
- Arthur Vesperini
- grid.9024.f0000 0004 1757 4641DSFTA, University of Siena, Via Roma 56, Siena, 53100 Italy ,grid.470215.5INFN Sezione di Perugia, Perugia, 06123 Italy ,grid.425378.f0000 0001 2097 1574QSTAR & CNR - Istituto Nazionale di Ottica, Largo Enrico Fermi 2, Firenze, 50125 Italy
| | - Ghofrane Bel-Hadj-Aissa
- grid.9024.f0000 0004 1757 4641DSFTA, University of Siena, Via Roma 56, Siena, 53100 Italy ,grid.470215.5INFN Sezione di Perugia, Perugia, 06123 Italy ,grid.425378.f0000 0001 2097 1574QSTAR & CNR - Istituto Nazionale di Ottica, Largo Enrico Fermi 2, Firenze, 50125 Italy
| | - Roberto Franzosi
- DSFTA, University of Siena, Via Roma 56, Siena, 53100, Italy. .,INFN Sezione di Perugia, Perugia, 06123, Italy. .,QSTAR & CNR - Istituto Nazionale di Ottica, Largo Enrico Fermi 2, Firenze, 50125, Italy.
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148
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Polino E, Poderini D, Rodari G, Agresti I, Suprano A, Carvacho G, Wolfe E, Canabarro A, Moreno G, Milani G, Spekkens RW, Chaves R, Sciarrino F. Experimental nonclassicality in a causal network without assuming freedom of choice. Nat Commun 2023; 14:909. [PMID: 36808157 PMCID: PMC9938195 DOI: 10.1038/s41467-023-36428-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 01/31/2023] [Indexed: 02/19/2023] Open
Abstract
In a Bell experiment, it is natural to seek a causal account of correlations wherein only a common cause acts on the outcomes. For this causal structure, Bell inequality violations can be explained only if causal dependencies are modeled as intrinsically quantum. There also exists a vast landscape of causal structures beyond Bell that can witness nonclassicality, in some cases without even requiring free external inputs. Here, we undertake a photonic experiment realizing one such example: the triangle causal network, consisting of three measurement stations pairwise connected by common causes and no external inputs. To demonstrate the nonclassicality of the data, we adapt and improve three known techniques: (i) a machine-learning-based heuristic test, (ii) a data-seeded inflation technique generating polynomial Bell-type inequalities and (iii) entropic inequalities. The demonstrated experimental and data analysis tools are broadly applicable paving the way for future networks of growing complexity.
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Affiliation(s)
- Emanuele Polino
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Davide Poderini
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy ,grid.411233.60000 0000 9687 399XInternational Institute of Physics, Federal University of Rio Grande do Norte, 59078-970, P. O. Box 1613 Natal, Brazil
| | - Giovanni Rodari
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Iris Agresti
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Alessia Suprano
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Gonzalo Carvacho
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Elie Wolfe
- Perimeter Institute for Theoretical Physics, 31 Caroline St. N, Waterloo, ON, N2L 2Y5, Canada.
| | - Askery Canabarro
- grid.411233.60000 0000 9687 399XInternational Institute of Physics, Federal University of Rio Grande do Norte, 59078-970, P. O. Box 1613 Natal, Brazil ,grid.411179.b0000 0001 2154 120XGrupo de Física da Matéria Condensada, Núcleo de Ciências Exatas-NCEx, Campus Arapiraca, Universidade Federal de ALagoas, 57309-005 Arapiraca, Alagoas Brazil
| | - George Moreno
- grid.411233.60000 0000 9687 399XInternational Institute of Physics, Federal University of Rio Grande do Norte, 59078-970, P. O. Box 1613 Natal, Brazil ,grid.411177.50000 0001 2111 0565Departamento de Computação, Universidade Federal Rural de Pernambuco, 52171-900 Recife, Pernambuco Brazil
| | - Giorgio Milani
- grid.7841.aDipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Roma, Italy
| | - Robert W. Spekkens
- grid.420198.60000 0000 8658 0851Perimeter Institute for Theoretical Physics, 31 Caroline St. N, Waterloo, ON N2L 2Y5 Canada
| | - Rafael Chaves
- International Institute of Physics, Federal University of Rio Grande do Norte, 59078-970, P. O. Box 1613, Natal, Brazil. .,School of Science and Technology, Federal University of Rio Grande do Norte, Natal, Brazil.
| | - Fabio Sciarrino
- Dipartimento di Fisica-Sapienza Università di Roma, P.le Aldo Moro 5, I-00185, Roma, Italy.
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149
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Bartolucci S, Birchall P, Bombín H, Cable H, Dawson C, Gimeno-Segovia M, Johnston E, Kieling K, Nickerson N, Pant M, Pastawski F, Rudolph T, Sparrow C. Fusion-based quantum computation. Nat Commun 2023; 14:912. [PMID: 36805650 PMCID: PMC9938229 DOI: 10.1038/s41467-023-36493-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 02/03/2023] [Indexed: 02/19/2023] Open
Abstract
The standard primitives of quantum computing include deterministic unitary entangling gates, which are not natural operations in many systems including photonics. Here, we present fusion-based quantum computation, a model for fault tolerant quantum computing constructed from physical primitives readily accessible in photonic systems. These are entangling measurements, called fusions, which are performed on the qubits of small constant sized entangled resource states. Probabilistic photonic gates as well as errors are directly dealt with by the quantum error correction protocol. We show that this computational model can achieve a higher threshold than schemes reported in literature. We present a ballistic scheme which can tolerate a 10.4% probability of suffering photon loss in each fusion, which corresponds to a 2.7% probability of loss of each individual photon. The architecture is also highly modular and has reduced classical processing requirements compared to previous photonic quantum computing architectures.
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150
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Dasari DBR. Thermodynamics of Quantum Spin-Bath Depolarization. Entropy (Basel) 2023; 25:340. [PMID: 36832706 PMCID: PMC9955735 DOI: 10.3390/e25020340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 02/01/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
We analyze here through exact calculations the thermodynamical effects in depolarizing a quantum spin-bath initially at zero temperature through a quantum probe coupled to an infinite temperature bath by evaluating the heat and entropy changes. We show that the correlations induced in the bath during the depolarizing process does not allow for the entropy of the bath to increase towards its maximal limit. On the contrary, the energy deposited in the bath can be completely extracted in a finite time. We explore these findings through an exactly solvable central spin model, wherein a central spin-1/2 system is homogeneously coupled to a bath of identical spins. Further, we show that, upon destroying these unwanted correlations, we boost the rate of both energy extraction and entropy towards their limiting values. We envisage that these studies are relevant for quantum battery research wherein both charging and discharging processes are key to characterizing the battery performance.
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