检索结果-内蒙古大学图书馆

Laser-Damage Attack Against Optical Attenuators in quantum Key Distribution

学校读者我要写书评

暂无评论

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

Tunable chiral anomalies and coherent transport on a honeycomb lattice

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Saroka, Vasil A. Kong, Fanmiao Downing, Charles A. Payod, Renebeth B. Fischer, Felix R. Sun, Xiankai Bogani, Lapo Center for Quantum Spintronics Department of Physics Norwegian University of Science and Technology TrondheimNO-7491 Norway Institute for Nuclear Problems Belarusian State University Bobruiskaya 11 Minsk220030 Belarus TBpack Ltd. 27 Old Gloucester Street LondonWC1N 3AX United Kingdom Department of Materials University of Oxford 16 Parks Road OxfordOX1 3PH United Kingdom Department of Physics and Astronomy University of Exeter ExeterEX4 4QL United Kingdom Institute of Mathematical Sciences and Physics University of the Philippines Laguna Los Baños4031 Philippines Department of Chemistry University of California BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Kavli Energy NanoSciences Institute The University of California Berkeley The Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Bakar Institute of Digital Materials for the Planet Division of Computing Data Science and Society University of California BerkeleyCA94720 United States Department of Electronic Engineering The Chinese University of Hong Kong Shatin New Territories Hong Kong

The search for energy efficient materials is urged not only by the needs of modern electronics but also by emerging applications in neuromorphic computing and artificial intelligence. Currently, there exist two mechanisms for achieving dissipationless transport: superconductivity and the quantum Hall effect. Here we reveal that dissipationless transport is theoretically achievable on a honeycomb lattice by rational design of chiral anomalies tunable without any magnetic fields. Breaking the usual assumption of commensurability and applying an external electric field lead to electronic modes exhibiting chiral anomalies capable of dissipationless transport in the material bulk, rather than on the edge. As the electric field increases, the system reaches a cubic-like dispersion material phase. While providing performance comparable to other known honeycomb lattice-based ballistic conductors such as an armchair nanotube, zigzag nanoribbon and hypothetical cumulenic carbyne, this scheme provides routes to a strongly correlated localization due to flat band dispersion and to exotic cubic dispersion material featuring a pitchfork bifurcation and a critical slowing down phenomena. These results open a new research avenue for the design of energy efficient information processing and higher-order dispersion materials. © 2023, CC BY.

关键词： Honeycomb structures

quantum electrodynamics in a topological waveguide

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Kim, Eunjong Zhang, Xueyue Ferreira, Vinicius S. Banker, Jash Iverson, Joseph K. Sipahigil, Alp Bello, Miguel González-Tudela, Alejandro Mirhosseini, Mohammad Oskar Painter, J. Thomas J. Watson Sr. Laboratory of Applied Physics Kavli Nanoscience Institute California Institute of Technology PasadenaCA91125 United States Institute for Quantum Information and Matter California Institute of Technology PasadenaCA91125 United States AWS Center for Quantum Computing PasadenaCA91125 United States Instituto de Ciencia de Materiales de Madrid CSIC Madrid28049 Spain Instituto de Física Fundamental IFF-CSIC Calle Serrano 113b Madrid28006 Spain Gordon and Betty Moore Laboratory of Engineering California Institute of Technology PasadenaCA91125 United States

While designing the energy-momentum relation of photons is key to many linear, non-linear, and quantum optical phenomena, a new set of light-matter properties may be realized by employing the topology of the photonic bath itself. In this work we investigate the properties of superconducting qubits coupled to a metamaterial waveguide based on a photonic analog of the Su-Schrieffer-Heeger model. We explore topologically-induced properties of qubits coupled to such a waveguide, ranging from the formation of directional qubit-photon bound states to topology-dependent cooperative radiation effects. Addition of qubits to this waveguide system also enables direct quantum control over topological edge states that form in finite waveguide systems, useful for instance in constructing a topologically protected quantum communication channel. More broadly, our work demonstrates the opportunity that topological waveguide-QED systems offer in the synthesis and study of many-body states with exotic long-range quantum correlations. Copyright © 2020, The Authors. All rights reserved.

关键词： Topology

Experimental simulation of shift operators in a quantum processor

学校读者我要写书评

暂无评论

Physical Review A 2019年第4期99卷 042328-042328页

作者： Xiangyu Kong Shijie Wei Jingwei Wen Tao Xin Gui-Lu Long State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China IBM Research Beijing 100085 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen 518055 China Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

The ability to implement quantum operations plays a fundamental role in manipulating quantum systems. Creation and annihilation operators which transform one quantum state into another by adding or subtracting a particle are crucial in constructing the quantum description of many-body quantum theory and quantum field theory. Here we present a quantum algorithm to perform the creation and annihilation operators by the linear combination of unitary operations associated with a two-qubit ancillary system. Our method can realize shift operators akin to creation and annihilation operators simultaneously in the subspace of the whole system. A prototypical experiment was performed with a four-qubit liquid-state nuclear magnetic resonance processor, demonstrating the algorithm via full-state tomography. With a postselected probability of about 50%, the shift operators are realized with a fidelity above 96%. Moreover, our method can be employed to quantum random walk in an arbitrary initial state. With the prosperous development of quantum computing, our work provides a quantum control technology to implement nonunitary evolution in a near-term quantum computer.

关键词： quantum algorithms quantum information architectures & platforms quantum simulation quantum walks

Creation of magnetic skyrmions in two-dimensional van der Waals ferromagnets by lattice distortion

学校读者我要写书评

暂无评论

Materials Today 2025年

作者： Tingjia Zhang Chendi Yang Xiaowei Lv Tuoyu Zhao Wu Shi Wei Li Jia Liang Renchao Che School of Materials and Chemistry University of Shanghai for Science and Technology Shanghai 200093 China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative Materials Academy for Engineering and Technology Advanced Coatings Research Center of Ministry of Education of China Fudan University Shanghai 200438 China State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai 200433 China Zhangjiang Fudan International Innovation Center Fudan University Shanghai 201210 China Department of Physics Fudan University Shanghai 200433 China College of Smart Materials and Future Energy and State Key Laboratory of Photovoltaic Science and Technology Fudan University Shanghai 200433 China

Two-dimensional (2D) van der Waals (vdW) ferromagnets provide an excellent platform for exploring exotic physical phenomena such as magnetic skyrmions and quantum topological phases. However, the centrosymmetric crystal structure inherent in these 2D vdW ferromagnets theoretically precludes the formation of magnetic skyrmions and topological phases. In this study, we investigate the origin of the absence of magnetic skyrmions in 2D vdW ferromagnets and propose an effective strategy to induce lattice distortion through doping, thereby enabling the formation of magnetic skyrmions. Specifically, through the integration of density functional theory (DFT) calculations and multiple experimental characterizations, we demonstrate that Co doping in Fe 3 GeTe 2 induces substantial lattice distortion, resulting in a transformation from a centrosymmetric to a non-centrosymmetric crystal structure. This structural modification enables the emergence of a considerable Dzyaloshinskii-Moriya interaction (DMI), which is a necessary condition for skyrmion formation. While the DFT results do not directly predict specific spin textures, the presence of Néel-type skyrmions is verified through Lorentz transmission electron microscopy (LTEM). Additionally, the scalar spin chirality of these magnetic skyrmions acts as a virtual magnetic field, thereby inducing the topological Hall effect (THE) in Co-doped Fe 3 GeTe 2 . Our findings present a reliable method to manipulate spin textures and induce the THE in 2D vdW ferromagnets with non-zero DMI through lattice distortion, offering a promising route for the development of vdW ferromagnet-based spintronic devices.

关键词：

Detecting chiral pairing and topological superuidity using circular dichroism

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Midtgaard, J.M. Wu, Zhigang Goldman, N. Bruun, G.M. Department of Physics and Astronomy Aarhus University Ny Munkegade Aarhus CDK-8000 Denmark Shenzhen Institute for Quantum Science and Engineering Department of Physics Southern University of Science and Technology Shenzhen518055 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China Center for Nonlinear Phenomena and Complex Systems Universite Libre de Bruxelles CP 231 Campus Plaine Brussels1050 Belgium

Realising and probing topological superuids is a key goal for fundamental science, with exciting technological promises. Here, we show that chiral px + ipy pairing in a two-dimensional topological superuid can be detected through circular dichroism, namely, as a difference in the excitation rates induced by a clockwise and counter-clockwise circular drive. For weak pairing, this difference is to a very good approximation determined by the Chern number of the superuid, whereas there is a nontopological contribution scaling as the superuid gap squared that becomes signifiant for stronger pairing. This gives rise to a competition between the experimentally driven goal to maximise the critical temperature of the superuid, and observing a signal given by the underlying topology. Using a combination of strong coupling Eliashberg and Berezinskii-Kosterlitz-Thouless theory, we analyse this tension for an atomic Bose-Fermi gas, which represents a promising platform for realising a chiral superuid. We identify a wide range of system parameters where both the critical temperature is high and the topological contribution to the dichroic signal is dominant. Copyright © 2020, The Authors. All rights reserved.

关键词： Dichroism

Emergence of kinematic space from quantum modular geometric tensor

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Huang, Xing Ma, Chen-Te Institute of Modern Physics Northwest University Xi’an710069 China NSFC-SPTP Peng Huanwu Center for Fundamental Theory Xi’an710127 China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi’an710069 China Asia Pacific Center for Theoretical Physics Pohang University of Science and Technology Gyeongsangbuk-do Pohang37673 Korea Republic of Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangdong Guangzhou510006 China School of Physics and Telecommunication Engineering South China Normal University Guangdong Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangdong Guangzhou510006 China The Laboratory for Quantum Gravity and Strings Department of Mathematics and Applied Mathematics University of Cape Town Private Bag Rondebosch7700 South Africa

We generalize the quantum Geometric Tensor by replacing a Hamiltonian with a modular Hamiltonian. The symmetric part of the quantum Geometric Tensor provides a Fubini-Study metric, and its anti-symmetric sector gives a Berry curvature. Now the generalization or quantum Modular Geometric Tensor gives a Kinematic Space and a modular Berry curvature. Here we demonstrate the emergence by focusing on a spherical entangling surface. We also use the result of the identity Virasoro block to relate the connected correlator of two Wilson lines to the two-point function of a modular Hamiltonian. This result realizes a novel holographic entanglement formula for two intervals of a general separation. This formula does not only hold for a classical gravity sector but also quantum Gravity. The formula also provides a new quantum Information interpretation to the connected correlators of Wilson lines as the mutual information. Our study provides an opportunity to explore quantum Kinematic Space through quantum Modular Geometric Tensor and hence go beyond symmetry. Copyright © 2021, The Authors. All rights reserved.

关键词： Tensors

Unboxing quantum black box models: Learning non-markovian dynamics

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Krastanov, Stefan Head-Marsden, Kade Zhou, Sisi Flammia, Steven T. Jiang, Liang Narang, Prineha John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Yale Quantum Institute Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06511 United States Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States AWS Center for Quantum Computing PasadenaCA91125 United States

Characterizing the memory properties of the environment has become critical for the high-fidelity control of qubits and other advanced quantum systems. However, current non-Markovian tomography techniques are either limited to discrete superoperators, or they employ machine learning methods, neither of which provide physical insight into the dynamics of the quantum system. To circumvent this limitation, we design learning architectures that explicitly encode physical constraints like the properties of completely-positive trace-preserving maps in a differential form. This method preserves the versatility of the machine learning approach without sacrificing the efficiency and fidelity of traditional parameter estimation methods. Our approach provides the physical interpretability that machine learning and opaque superoperators lack. Moreover, it is aware of the underlying continuous dynamics typically disregarded by superoperator-based tomography. This paradigm paves the way to noise-aware optimal quantum control and opens a path to exploiting the bath as a control and error mitigation resource. Copyright © 2020, The Authors. All rights reserved.

关键词： quantum optics

Wide-field fluorescent nanodiamond spin measurements toward real-time large-area intracellular quantum thermometry

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Nishimura, Yushi Oshimi, Keisuke Umehara, Yumi Kumon, Yuka Miyaji, Kazu Yukawa, Hiroshi Shikano, Yutaka Matsubara, Tsutomu Fujiwara, Masazumi Baba, Yoshinobu Teki, Yoshio Department of Chemistry Osaka City University Sumiyoshi-ku Osaka558-8585 Japan Department of Biomolecular Engineering Graduate School of Engineering Nagoya University Nagoya464-8603 Japan Institute of Nano-Life-Systems Institutes of Innovation for Future Society Nagoya University Nagoya464-8603 Japan Institute of Quantum Life Science National Institutes for Quantum and Radiological Science and Technology Chiba Japan Quantum Computing Center Keio University 3-14-1 Hiyoshi Kohoku Yokohama223-8522 Japan Institute for Quantum Studies Chapman University 1 University Dr. OrangeCA92866 United States Department of Anatomy and Regenerative Biology Graduate School of Medicine Osaka City University Osaka545-8585 Japan

In this study, we analyze the operational process of nanodiamond (ND) quantum thermometry based on wide-field detection of optically detected magnetic resonance (ODMR) of nitrogen vacancy centers, and compare its performance with that of confocal ODMR detection. We found that (1) the thermometry results are significantly affected by the shape and size of the camera region of interest (ROI) surrounding the target NDs and that (2) by properly managing the ROI and acquisition parameters of the camera, a temperature precision comparable to confocal detection in living cells can be obtained by wide-field ODMR. Our results are significant to the development of camera-based real-time large-area quantum thermometry of living cells. Copyright © 2020, The Authors. All rights reserved.

关键词： Nanodiamonds