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Laser-Damage Attack Against Optical Attenuators in quantum Key Distribution

Physical Review Applied 2020年第3期13卷 034017-034017页

作者： Anqi Huang Ruoping Li Vladimir Egorov Serguei Tchouragoulov Krtin Kumar Vadim Makarov Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha 410073 People’s Republic of China Institute for Quantum Computing University of Waterloo Waterloo Ontario N2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo Waterloo Ontario N2L 3G1 Canada Department of Physics and Astronomy University of Waterloo Waterloo Ontario N2L 3G1 Canada Faculty of Photonics and Optical Information ITMO University 199034 Kadetskaya line 3b St. Petersburg Russia QGLex Incorporated 105 Schneider Road Suite 111 Ottawa Ontario K2K 1Y3 Canada Russian Quantum Center Skolkovo Moscow 121205 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai 201315 People’s Republic of China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow 119049 Russia

Many quantum key distribution systems employ a laser followed by an optical attenuator to prepare weak coherent states in the source. Their mean photon number must be precalibrated to guarantee the security of key distribution. Here we experimentally show that this calibration can be broken with a high-power laser attack. We test four fiber-optic attenuator types used in quantum key distribution systems, and find that two of them exhibit a permanent decrease in attenuation after laser damage. This results in higher mean photon numbers in the prepared states and may allow an eavesdropper to compromise the key.

关键词： Light-matter interaction Photon statistics Photonics quantum communication quantum cryptography quantum optics Devices Fiber lasers

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Microresonators enhancing long-distance dynamical entanglement generation in chiral quantum networks

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Physical Review A 2020年第5期101卷 053861-053861页

作者： Wai-Keong Mok Jia-Bin You Leong-Chuan Kwek Davit Aghamalyan Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore 117543 Singapore Department of Electronics and Photonics Institute of High Performance Computing 1 Fusionopolis Way 16-16 Connexis Singapore 138632 Singapore MajuLab CNRS-UNS-NUS-NTU International Joint Research Unit UMI 3654 Singapore National Institute of Education and Institute of Advanced Studies Nanyang Technological University 1 Nanyang Walk Singapore 637616 Singapore School of Electrical and Electronic Engineering Block S2.1 50 Nanyang Avenue Singapore 639798 Singapore

Chiral quantum networks provide a promising route for realizing quantum information processing and quantum communication. Here we describe how two distant quantum nodes of chiral quantum network become dynamically entangled by a photon transfer through a common one-dimensional chiral waveguide. We harness the directional asymmetry in chirally coupled single-mode ring resonators to generate an entangled state between two atoms. We report a concurrence of up to 0.969, a huge improvement over 0.736, which was suggested and analyzed in great detail in Gonzalez-Ballestero et al. [Phys. Rev. B 92, 155304 (2015)]. This significant enhancement is achieved by introducing microresonators which serve as an efficient photonic interface between light and matter. The robustness of our protocol to experimental imperfections such as fluctuations in internodal distance, imperfect chirality, various detunings, and atomic spontaneous decay is demonstrated. Our proposal can be utilized for long-distance entanglement generation in quantum networks, which is a key ingredient for many applications in quantum computing and quantum information processing.

关键词： Light-matter interaction quantum entanglement quantum networks

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Non-Markovianity, information backflow and system-environment correlation for open-quantum-system processes

arXiv

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arXiv 2019年

作者： Hsieh, Yun-Yi Su, Zheng-Yao Goan, Hsi-Sheng Department of Physics and Center for Theoretical Physics National Taiwan University Taipei10617 Taiwan National Center for High-Performance Computing Hsinchu300 Taiwan Center for Quantum Science and Engineering National Taiwan University Taipei10617 Taiwan

A Markovian process of a system is defined classically as a process in which the future state of the system is fully determined by only its present state, not by its previous history. There have been several measures of non-Markovianity to quantify the degrees of non-Markovian effect in a process of an open quantum system based on information backflow from the environment to the system. However, the condition for the witness of the system information backflow does not coincide with the classical definition of a Markovian process. Recently, a new measure with a condition that coincides with the classical definition in the relevant limit has been proposed. Here, we focus on the new definition (measure) for quantum non-Markovian processes, and characterize the Markovian condition as a quantum process that has no information backflow through the reduced environment state (IBTRES) and no system-environment correlation effect (SECE). The action of IBTRES produces non-Markovian effects by flowing the information of quantum operations performed by an experimenter at earlier times back to the system through the environment, while the SECE can produce non-Markovian effect without carrying any earlier quantum operation information. We give the necessary and sufficient conditions for no IBTRES and no SECE, respectively, and show that a process is Markovian if and only if it has no IBTRES and no SECE. The quantitative measures and algorithms for calculating non-Markovianity, IBTRES and soly-SECE are explicitly presented. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum optics

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Mapping the intrinsic photocurrent streamlines through micromagnetic heterostructure devices

arXiv

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arXiv 2020年

作者： Mayes, Morgan Farahmand, Farima Grossnickle, Maxwell Lohmann, Mark Aldosary, Mohammed Li, Junxue Aji, Vivek Shi, Jing Song, Justin C.W. Gabor, Nathaniel M. Department of Physics and Astronomy University of California 900 University Avenue RiversideCA92521 United States Laboratory of Quantum Materials Optoelectronics Materials Science and Engineering Building University of California Room 179 RiversideCA92521 United States School of Physical and Mathematical Sciences Division of Physics and Applied Physics Nanyang Technological University Singapore637371 Singapore Institute of High Performance Computing Agency of Science Technology and Research Singapore138632 Singapore

Like air flowing over a wing, optimizing the flow of electronic charge is essential to the operation of nanoscale devices. Unfortunately, the delicate interplay of charge, spin, and heat in complex devices has precluded detailed imaging of charge flow. Here, we report on the visualization of intrinsic charge current streamlines through yttrium iron garnet micromagnetic heterostructures. Scanning photovoltage microscopy of precisely designed devices leads to striking spatial patterns, with prominent photovoltage features emerging in corners and narrow constrictions. These patterns, which evolve continuously with rotation of an external magnetic field, enable rich spatial mapping of fluid-like flow. Taking inspiration from aerodynamic Clark Y airfoils, we engineer micromagnetic wing shaped devices, called electrofoils, which allow us to precisely contort, compress and decompress flowlines of electronic charge. Copyright © 2020, The Authors. All rights reserved.

关键词： Mapping

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Observing Geometry of quantum States in a Three-Level System

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Physical Review Letters 2020年第15期125卷 150401-150401页

作者： Jie Xie Aonan Zhang Ningping Cao Huichao Xu Kaimin Zheng Yiu-Tung Poon Nung-Sing Sze Ping Xu Bei Zeng Lijian Zhang National Laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and Manipulation (Ministry of Education) College of Engineering and Applied Sciences and School of Physics Nanjing University Nanjing 210093 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Department of Mathematics & Statistics University of Guelph Guelph N1G 2W1 Ontario Canada Institute for Quantum Computing University of Waterloo Waterloo N2L 3G1 Ontario Canada Department of Mathematics Iowa State University Ames Iowa 50011 USA Department of Applied Mathematics The Hong Kong Polytechnic University 999077 Hong Kong China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha 410073 China Department of Physics The Hong Kong University of Science and Technology Clear Water Bay Kowloon 999077 Hong Kong China

In quantum mechanics, geometry has been demonstrated as a useful tool for inferring nonclassical behaviors and exotic properties of quantum systems. One standard approach to illustrate the geometry of quantum systems is to project the quantum state space onto the Euclidean space via measurements of observables on the system. Despite the great success of this method in studying two-level quantum systems (qubits) with the celebrated Bloch sphere representation, it is still difficult to reveal the geometry of multidimensional quantum systems. Here we report the first experiment measuring the geometry of such projections beyond the qubit. Specifically, we observe the joint numerical ranges of a triple of observables in a three-level photonic system, providing a complete classification of these ranges. We further show that the geometry of different classes reveals ground-state degeneracies of a Hamiltonian as a linear combination of the observables, which is related to quantum phases in the thermodynamic limit. Our results offer a versatile geometric approach for exploring the properties of higher-dimensional quantum systems.

关键词： Geometric & topological phases quantum foundations quantum measurements quantum phase transitions

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eROSITA clusters dynamical state and their impact on the BCG luminosity

arXiv

引用

arXiv 2025年

作者： Zenteno, A. Kluge, M. Kharkrang, R. Hernandez-Lang, D. Damke, G. Saro, A. Monteiro-Oliveira, R. Carrasco, E.R. Salvato, M. Comparat, J. Fabricius, M. Snigula, J. Arevalo, P. Cuevas, H. Castellon, J.L. Nilo Ramirez, A. Astudillo, S. Véliz Landriau, M. Myers, A.D. Schlafly, E. Valdes, F. Weaver, B. Mohr, J.J. Grandis, S. Klein, M. Liu, A. Bulbul, E. Zhang, X. Sanders, J.S. Bahar, Y.E. Ghirardini, V. Ramos, M. Balzer, F. Cerro Tololo Inter-American Observatory NSF’s National Optical-Infrared Astronomy Research Laboratory Casilla 603 La Serena Chile Max Planck Institute for Extraterrestrial Physics Giessenbachstrasse 1 Garching85748 Germany Universitè Paris-Saclay CNRS Institut dÁstrophysique Spatiale Orsay91405 France Faculty of Physics Ludwig-Maximilians-Universität München Scheinerstr. 1 Munich81679 Germany INAF - Osservatorio Astronomico di Trieste via G. B. Tiepolo 11 Trieste34143 Italy IFPU - Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34014 Italy Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 Trieste34131 Italy INFN - National Institute for Nuclear Physics Via Valerio 2 TriesteI-34127 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy Institute of Astronomy and Astrophysics Academia Sinica Taipei10617 Taiwan International Gemini Observatory NSF NOIRLab Casilla 603 La Serena Chile Instituto de Física y Astronomía Universidad de Valparaíso Gran Bretaña 1111 Valparaíso Chile Chile Departamento de Astronomía Universidad de La Serena Av. Raúl Bitrán 1305 La Serena Chile Lawrence Berkeley National Laboratory 1 Cyclotron Road BerkeleyCA94720 United States Department of Physics & Astronomy University of Wyoming 1000 E. University Dept. 3905 LaramieWY82071 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States 950 N. Cherry Ave TucsonAZ85732 United States Universität Innsbruck Institut für Astro- und Teilchenphysik Technikerstr. 25/8 Innsbruck6020 Austria

Context. The SRG (Spectrum Roentgen Gamma)/eROSITA first public release contains 12,247 clusters and groups from the first 6 months of operation. We use the offset between the Brightest Cluster Galaxy (BCG) and the X–ray peak (DBCG−X) to classify the cluster dynamical state of 3,946 galaxy clusters and groups. Aims. We aim to investigate the evolution of the merger and relaxed cluster distributions with redshift and mass, and their impact on the BCG. Methods. We use the X–ray peak from the eROSITA survey and the BCG position from the DECaLS DR10 optical data, which includes the DECam eROSITA Survey optical data, to measure the DBCG−X offset. We model the distribution of DBCG−X, in units of r500, as the sum of two Rayleigh distributions representing the cluster’s relaxed and disturbed populations, and explore their evolution with redshift and mass. To explore the impact of the cluster’s dynamical state on the BCG luminosity, we separate the main sample according to the dynamical state. We define clusters as relaxed if DBCG−X500, disturbed if DBCG−X>0.5r500, and as ‘diverse’ if 0.25BCG−X Copyright © 2025, The Authors. All rights reserved.

关键词： Photons

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Optimal Machine Intelligence Near the Edge of Chaos

arXiv

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arXiv 2019年

作者： Feng, Ling Lai, Choy Heng Institute of High Performance Computing A*STAR 138632 Singapore Department of Physics National University of Singapore Singapore117551 Centre for Quantum Technologies National University of Singapore 117543 Singapore NUS Graduate School for Integrative Sciences and Engineering Singapore119077

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quantum neural networks with data re-uploading for urban traffic time series forecasting

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Scientific Reports 2025年第1期15卷 1-21页

作者： Schetakis, Nikolaos Bonfini, Paolo Alisoltani, Negin Blazakis, Konstantinos Tsintzos, Symeon I. Askitopoulos, Alexis Aghamalyan, Davit Fafoutellis, Panagiotis Vlahogianni, Eleni I. Computational Mechanics and Optimization Laboratory School of Production Engineering and Management Technical University of Crete Chania 73100 Greece Quantum Innovation Pc Chania 73100 Greece Alma-Sistemi Srl Guidonia 00012 Italy Univ Gustave Eiffel COSYS GRETTIA Paris F-77454 France Department of Electrical and Computer Engineering Hellenic Mediterranean University Heraklion 71410 Greece QUBITECH Pc Athens 15231 Greece Institute of High Performance Computing A*STAR (Agency for Science Technology and Research) 1 Fusionopolis Way #16-16 Connexis Singapore 138632 Singapore Department of Transportation Planning and Engineering School of Civil Engineering National Technical University of Athens 5 Iroon Polytechniou Str Zografou Campus Athens 157 73 Greece

Accurate traffic forecasting plays a crucial role in modern Intelligent Transportation Systems (ITS), as it enables real-time traffic flow management, reduces congestion, and improves the overall efficiency of urban transportation networks. With the rise of quantum Machine Learning (QML), it has emerged a new paradigm possessing the potential to enhance predictive capabilities beyond what classical machine learning models can achieve. In the present work we pursue a heuristic approach to explore the potential of QML, and focus on a specific transport issue. In particular, as a case study we investigate a traffic forecast task for a major urban area in Athens (Greece), for which we possess high-resolution data. In this endeavor we explore the application of quantum Neural Networks (QNN), and, notably, we present the first application of quantum data re-uploading in the context of transport forecasting. This technique allows quantum models to better capture complex patterns, such as traffic dynamics, by repeatedly encoding classical data into a quantum state. Aside from providing a prediction model, we spend considerable effort in comparing the performance of our hybrid quantum-classical neural networks with classical deep learning approaches. We observe that, in fully connected network settings, hybrid quantum-classical models consistently underperform, with median scores approximately 10% worse than their purely classical counterparts across different configurations. In contrast, recursive architectures with data re-uploading show the opposite trend: hybrid models achieved up to 5% better median scores under comparable complexity settings. Additionally, these hybrid models converged in fewer training epochs, indicating improved training efficiency. Our results show that hybrid models achieve competitive accuracy with state-of-the-art classical methods, especially when the number of qubits and re-uploading blocks is increased. While the classical models demonstrate l

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Practical security of continuous-variable quantum key distribution with reduced optical attenuation

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Physical Review A 2019年第1期100卷 012313-012313页

作者： Yi Zheng Peng Huang Anqi Huang Jinye Peng Guihua Zeng College of Information Science and Technology Northwest University Xi'an 710127 Shaanxi China State Key Laboratory of Advanced Optical Communication Systems and Networks and Center of Quantum Information Sensing and Processing Shanghai Jiao Tong University Shanghai 200240 China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha 410073 China Greatwall Quantum Laboratory China Greatwall Technology Changsha 410205 China

In a practical continuous-variable quantum key distribution (CVQKD) system, the optical attenuator can adjust the Gaussian-modulated coherent states and the local oscillator signal to an optimal value for guaranteeing the security of the system and optimizing the performance of the system. However, the performance of the optical attenuator may deteriorate due to the intentional and unintentional damage of the device. In this paper, we investigate the practical security of a CVQKD system with reduced optical attenuation. We find that the secret key rate of the system may be overestimated based on the investigation of parameter estimation under the effects of reduced optical attenuation. This opens a security loophole for Eve to successfully perform an intercept-resend attack in a practical CVQKD system. To close this loophole, we add an optical fuse at Alice's output port and design a scheme to monitor the level of optical attenuation in real time, which can make the secret key rate of the system evaluated precisely. The analysis shows that these countermeasures can effectively resist this potential attack.

关键词： quantum communication quantum cryptography quantum information processing with continuous variables

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Edge-induced topological phase transition of the quantum Hall state at half filling

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Physical Review B 2019年第16期99卷 161108(R)-161108(R)页

作者： Bo Yang Na Jiang Xin Wan Jie Wang Zi-Xiang Hu Division of Physics and Applied Physics Nanyang Technological University Singapore 637371 Singapore Complex Systems Group Institute of High Performance Computing A*STAR Singapore 138632 Singapore Zhejiang Institute of Modern Physics Zhejiang University Hangzhou 310027 People's Republic of China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 People's Republic of China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 People's Republic of China Department of Physics Princeton University Princeton New Jersey 08544 USA Department of Physics Chongqing University Chongqing 401331 People's Republic of China

We show that in quantum Hall systems at half filling, edge potentials alone can drive transitions between the Pfaffian and anti-Pfaffian topological phases. We conjecture this is true in realistic systems even in the presence of bulk interactions that weakly break the particle-hole symmetry. The strong effects of edge potentials could be understood from different topological shifts of competing phases at half filling, manifested on the disk geometry as the variation of orbital numbers at a fixed number of particles. In particular, we show analytically that the particle-hole conjugation of Hamiltonians on the disk is equivalent to the tuning of edge potentials, which allows us to explicitly demonstrate the phase transition numerically. The importance of edge potentials in various experimental contexts, including the recently discovered particle-hole symmetric phase, is also discussed.

关键词： Fractional quantum Hall effect Mesoscopics Topological phases of matter

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