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Resource Marginal Problems

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arXiv 2022年

作者： Hsieh, Chung-Yun Tabia, Gelo Noel M. Yin, Yu-Chun Liang, Yeong-Cherng H. H. Wills Physics Laboratory University of Bristol Tyndall Avenue BristolBS8 1TL United Kingdom ICFO - Institut de Ciències Fotòniques The Barcelona Institute of Science and Technology Castelldefels08860 Spain Foxconn Quantum Computing Research Center Taipei114 Taiwan National Cheng Kung University Tainan701 Taiwan Physics Division National Center for Theoretical Sciences Taipei106319 Taiwan Center for Quantum Technology National Tsing Hua University Hsinchu300 Taiwan Institute of Communications Engineering National Yang Ming Chiao Tung University Hsinchu300093 Taiwan

We introduce the resource marginal problems, which concern the possibility of having a resource-free target subsystem compatible with a given collection of marginal density matrices. By identifying an appropriate choice of resource R and target subsystem T, our problems reduce, respectively, to the well-known marginal problems for quantum states and the problem of determining if a given quantum system is a resource. More generally, we say that a set of marginal states is resource-free incompatible with a target subsystem T if all global states compatible with this set must result in a resourceful state in T of type R. We show that this incompatibility induces a resource theory that can be quantified by a monotone and obtain necessary and sufficient conditions for this monotone to be computable as a conic program with finite optimum. We further show, via the corresponding witnesses, that (1) resource-free incompatibility is equivalent to an operational advantage in some channel-discrimination tasks, and (2) some specific cases of such tasks fully characterize the convertibility between marginal density matrices exhibiting resource-free incompatibility. Through our framework, one sees a clear connection between any marginal problem—which implicitly involves some notion of incompatibility—for quantum states and a resource theory for quantum states. We also establish a close connection between the physical relevance of resource marginal problems and the ground state properties of certain many-body Hamiltonians. In terms of application, the universality of our framework leads, for example, to a further quantitative understanding of the incompatibility associated with the recently-proposed entanglement marginal problems and entanglement transitivity problems. © 2022, CC BY.

关键词： Ground state

Hidden magnetism uncovered in charge ordered bilayer kagome material ScV6Sn6

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arXiv 2023年

作者： Guguchia, Z. Gawryluk, D.J. Shin, Soohyeon Hao, Z. Mielke, C. Das, D. Plokhikh, I. Liborio, L. Shenton, K. Hu, Y. Sazgari, V. Medarde, M. Deng, H. Cai, Y. Chen, C. Jiang, Y. Amato, A. Shi, M. Hasan, M.Z. Yin, J.-X. Khasanov, R. Pomjakushina, E. Luetkens, H. Laboratory for Muon Spin Spectroscopy Paul Scherrer Institute Villigen PSICH-5232 Switzerland Laboratory for Multiscale Materials Experiments Paul Scherrer Institut Villigen PSI5232 Switzerland Department of Physics Southern University of Science and Technology Guangdong Shenzhen518055 China Physik-Institut Universität Zürich Winterthurerstrasse 190 ZürichCH-8057 Switzerland Scientific Computing Department Science & Technology Facilities Council Rutherford Appleton Laboratory DidcotOX11 0QX United Kingdom Photon Science Division Paul Scherrer Institut Villigen PSICH-5232 Switzerland Laboratory for Multiscale Materials Experiments Paul Scherrer Institut Villigen PSICH-5232 Switzerland Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Department of Physics Princeton University PrincetonNJ08544 United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08540 United States Quantum Science Center Oak RidgeTN37831 United States

Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered kagome material ScV6Sn6 does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe a striking enhancement of the internal field width sensed by the muon ensemble, which takes place within the charge ordered state. More remarkably, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. Taken together with the hidden magnetism found in AV3Sb5 (A = K, Rb, Cs) and FeGe kagome systems, our results suggest ubiqitous time-reversal symmetry-breaking in charge ordered kagome lattices. Copyright © 2023, The Authors. All rights reserved.

关键词： Charged particles

Solving systems of Boolean multivariate equations with quantum annealing

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arXiv 2021年

作者： Ramos-Calderer, Sergi Bravo-Prieto, Carlos Lin, Ruge Bellini, Emanuele Manzano, Marc Aaraj, Najwa Latorre, José I. Quantum Research Centre Technology Innovation Institute Abu Dhabi United Arab Emirates Universitat de Barcelona Martí i Franquès 1 Barcelona08028 Spain Cryptography Research Centre Technology Innovation Institute Abu Dhabi United Arab Emirates Sandbox@Alphabet Mountain ViewCA United States Electronics and Computing Department Faculty of Engineering Mondragon Unibertsitatea Mondragon Spain Centre for Quantum Technologies National University of Singapore Singapore

Polynomial systems over the binary field have important applications, especially in symmetric and asymmetric cryptanalysis, multivariate-based post-quantum cryptography, coding theory, and computer algebra. In this work, we study the quantum annealing model for solving Boolean systems of multivariate equations of degree 2, usually referred to as the Multivariate Quadratic problem. We present different methodologies to embed the problem into a Hamiltonian that can be solved by available quantum annealing platforms. In particular, we provide three embedding options, and we highlight their differences in terms of quantum resources. Moreover, we design a machine-agnostic algorithm that adopts an iterative approach to better solve the problem Hamiltonian by repeatedly reducing the search space. Finally, we use D-Wave devices to successfully implement our methodologies on several instances of the Multivariate Quadratic problem. Copyright © 2021, The Authors. All rights reserved.

关键词： Hamiltonians

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Many-body echo

Physical Review A 2020年第1期102卷 011301(R)-011301(R)页

作者： Yang-Yang Chen Pengfei Zhang Wei Zheng Zhigang Wu Hui Zhai Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen 518055 China CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China Institute for Advanced Study Tsinghua University Beijing 100084 China Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei 230026 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen 518055 China

In this Rapid Communication, we propose a protocol to reverse a quantum many-body dynamic process. We name it “many-body echo” because the underlying physics is closely related to the spin echo effect in nuclear magnetic resonance systems. We consider a periodical modulation of the interaction strength in a weakly interacting Bose condensate, which resonantly excites quasiparticles from the condensate. A dramatic phenomenon is that, after pausing the interaction modulation for half a period and then continuing on with the same modulation, nearly all the excited quasiparticles in the resonance modes will be absorbed back into the condensate. During the intermediate half-period, the free evolution introduces a π phase, which plays a role reminiscent of that played by the π pulse in the spin echo. Comparing our protocol with another one implemented by the Chicago group in a recent experiment, we find that ours is more effective at reversing the many-body process. The difference between these two schemes manifests the physical effect of the micromotion in the Floquet theory.

关键词： Bose-Einstein condensates Bosons Floquet systems Ultracold gases

Experimental verification of entangled states in the adversarial scenario

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Physical Review Applied 2025年第6期23卷 064005-064005页

作者： Wen-Hao Zhang Zihao Li Gong-Chu Li Xu-Song Hong Huangjun Zhu Geng Chen Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui 230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China School of Physics and Optoelectronics Engineering Anhui University Hefei Anhui 230601 China State Key Laboratory of Surface Physics Department of Physics and Center for Field Theory and Particle Physics Fudan University Shanghai 200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai 200433 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China Hefei National Laboratory Hefei 230088 China

Efficient verification of entangled states is crucial to many applications in quantum information processing. However, the effectiveness of standard quantum state verification (QSV) is based on the condition of independent and identical distribution (IID), which impedes its applications in many practical scenarios. Here we demonstrate a defensive QSV protocol, which is effective in all kinds of non-IID scenarios, including the extremely challenging adversarial scenario. To this end, we build a high-speed preparation-and-measurement apparatus controlled by quantum random-number generators. Our experiments clearly show that standard QSV protocols often provide unreliable fidelity certificates in non-IID scenarios. In sharp contrast, the defensive QSV protocol based on a homogeneous strategy can provide reliable and nearly tight fidelity certificates at comparable high efficiency, even under malicious attacks. Moreover, our scheme is tolerant of the imperfections in a realistic experiment, which is very appealing to practical applications.

关键词： quantum entanglement

Erratum:Frustrated Magnetic Interactions and Quenched Spin Fluctuations in CrAs[***.39,127501(2022)]

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Chinese Physics Letters 2023年第2期40卷 69-69页

作者： Yayuan Qin Yao Shen Yiqing Hao Hongliang Wo Shoudong Shen Russell A. Ewings Yang Zhao Leland W. Harriger Jeffrey W. Lynn Jun Zhao State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Shanghai Qizhi Institute Shanghai 200232 China ISIS Pulsed Neutron and Muon Source STFC Rutherford Appleton Laboratory Harwell Campus Didcot Oxon OX11 0QX United Kingdom NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg MD 20899 USA Department of Materials Science and Engineering University of Maryland College Park MD 20742 USA Institute of Nanoelectronics and Quantum Computing Fudan University Shanghai 200433 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China

Frustrated Magnetic Interactions and Quenched Spin Fluctuations in CrAs

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arXiv 2022年

作者： Qin, Yayuan Shen, Yao Hao, Yiqing Wo, Hongliang Shen, Shoudong Ewings, Russell A. Zhao, Yang Harriger, Leland W. Lynn, Jeffrey W. Zhao, Jun State Key Laboratory of Surface Physics Department of Physics Fudan University Shanghai200433 China Shanghai Qizhi Institute Shanghai200232 China ISIS Pulsed Neutron and Muon Source STFC Rutherford Appleton Laboratory Harwell Campus Didcot OxonOX11 0QX United Kingdom NIST Center for Neutron Research National Institute of Standards and Technology GaithersburgMD20899 United States Department of Materials Science and Engineering University of Maryland College ParkMD20742 United States Institute of Nanoelectronics and Quantum Computing Fudan University Shanghai200433 China Shanghai Research Center for Quantum Sciences Shanghai201315 China

The discovery of pressure-induced superconductivity in helimagnets (CrAs, MnP) has attracted considerable interest in understanding the relationship between complex magnetism and unconventional superconductivity. However, the nature of the magnetism and magnetic interactions that drive the unusual double-helical magnetic order in these materials remains unclear. Here, we report neutron scattering measurements of magnetic excitations in CrAs single crystals at ambient pressure. Our experiments reveal well defined spin wave excitations up to about 150 meV with a pseudogap below 7 meV, which can be effectively described by the Heisenberg model with nearest neighbor exchange interactions. Most surprisingly, the spin excitations are largely quenched above the Néel temperature, in contrast to cuprates and iron pnictides where the spectral weight is mostly preserved in the paramagnetic state. Our results suggest that the helimagnetic order is driven by strongly frustrated exchange interactions, and that CrAs is at the verge of itinerant and correlation-induced localized states, which is therefore highly pressure-tunable and favorable for superconductivity. © 2022, CC BY-NC-ND.

关键词： Neutron scattering

Flat band, tunable chiral anomaly, and pitchfork bifurcation in a honeycomb lattice

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Physical Review B 2024年第19期110卷 195134-195134页

作者： V. A. Saroka F. Kong L. Bogani C. A. Downing R. B. Payod F. R. Fischer Center for Quantum Spintronics Department of Physics Norwegian University of Science and Technology NO-7491 Trondheim Norway Department of Materials University of Oxford 16 Parks Road OX1 3PH Oxford United Kingdom Department of Physics and Astronomy University of Exeter Exeter EX4 4QL United Kingdom Institute of Physics University of the Philippines - Los Baños College Los Baños Laguna 4030 Philippines Department of Chemistry University of California Berkeley California 94720 USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory Berkeley California 94720 USA and Bakar Institute of Digital Materials for the Planet Division of Computing Data Science and Society University of California Berkeley California 94720 USA Department of Electronic Engineering The Chinese University of Hong Kong Shatin New Territories Hong Kong SAR China

Chiral anomaly engineering has been established as one of the mechanisms for achieving energy efficient dissipationless transport. Here we show how to design tunable chiral anomalies in a honeycomb lattice free of any magnetic fields. By applying an external electric field to a flat band material with a broken inversion symmetry, we generate electronic modes exhibiting chiral anomalies capable of disorder resilient transport in the bulk of the material. As the electric field increases, the system exhibits an unusual cubic-like dispersion. By providing a performance comparable to other honeycomb lattice-based ballistic conductors such as armchair nanotube, zigzag nanoribbon and hypothetical cumulenic carbyne, this scheme opens a new research avenue for the design of energy efficient information processing and higher-order dispersion materials.

关键词： Dirac fermions Edge states Electronic structure Flat bands Valley degrees of freedom Valleytronics

Novel characterisation of dopant-based qubits

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arXiv 2021年

作者： Voisin, Benoit Salfi, J. Rahman, R. Rogge, S. Silicon Quantum Computing SydneyNSW2052 Australia School of Physics The University of New South Wales SydneyNSW2052 Australia Stewart Blusson Quantum Matter Institute Department of Electrical and Computer Engineering University of British Columbia VancouverBCV6T 1Z4 Canada Centre for Quantum Computation and Communication Technology School of Physics The University of New South Wales SydneyNSW2052 Australia

Silicon is a leading qubit platform thanks to the exceptional coherence times that can be achieved and to the available commercial manufacturing platform for integration. Building scalable quantum processing architectures relies on accurate quantum state manipulation, which can only be achieved through a complete understanding of the underlying quantum state properties. This article reviews the electrical methods that have been developed to probe the quantum states encoded in individual and interacting atom qubits in silicon, from the pioneering single electron tunneling spectroscopy framework in nanoscale transistors, to radio frequency reflectometry to probe coherence properties and scanning tunneling microscopy to directly image the wave function at the atomic scale. Together with the development of atomistic simulations of realistic devices, these methods are today applied to other emerging dopant and optically addressable defect states to accelerate the engineering of quantum technologies in silicon. Copyright © 2021, The Authors. All rights reserved.

关键词： Scanning tunneling microscopy