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arXiv 2024年

作者： Wang, Ping Chen, Chong Liao, Hao Vorobyov, Vadim V. Wrachtrup, Jörg Liu, Ren-Bao College of Education for the Future Beijing Normal University Zhuhai519087 China Department of Physics The Chinese University of Hong Kong New Territories Shatin Hong Kong Centre for Quantum Coherence The Chinese University of Hong Kong New Territories Shatin Hong Kong The Hong Kong Institute of Quantum Information Science and Technology The Chinese University of Hong Kong New Territories Shatin Hong Kong National Engineering Laboratory on Big Data System Computing Technology Guangdong Province Engineering Center of China-made High Performance Data Computing System College of Computer Science and Software Engineering Shenzhen University Shenzhen518060 China 3rd Institute of Physics Research Center SCoPE and IQST University of Stuttgart Stuttgart70569 Germany New Cornerstone Science Laboratory The Chinese University of Hong Kong New Territories Shatin Hong Kong

Test of macroscopic realism (MR) is key to understanding the foundation of quantum mechanics. Due to the existence of the non-invasive measurability loophole and other interpretation loopholes, however, such test remains an open question. Here we propose a general inequality based on high-order correlations of measurements for a loophole-free test of MR at the weak signal limit. Importantly, the inequality is established using the statistics of raw data recorded by classical devices, without requiring a specific model for the measurement process, so its violation would falsify MR without the interpretation loophole. The non-invasive measurability loophole is also closed, since the weak signal limit can be verified solely by measurement data (using the relative scaling behaviors of different orders of correlations). We demonstrate that the inequality can be broken by a quantum spin model. The inequality proposed here provides an unambiguous test of the MR principle and is also useful to characterizing quantum coherence. Copyright © 2024, The Authors. All rights reserved.

关键词： quantum theory

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Critical phase and spin sharpening in SU(2)-symmetric monitored quantum circuits

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Physical Review B 2023年第5期108卷 054307-054307页

作者： Shayan Majidy Utkarsh Agrawal Sarang Gopalakrishnan Andrew C. Potter Romain Vasseur Nicole Yunger Halpern Perimeter Institute for Theoretical Physics Waterloo Ontario Canada N2L 2Y5 Institute for Quantum Computing University of Waterloo Waterloo Ontario Canada N2L 3G1 Kavli Institute for Theoretical Physics University of California Santa Barbara California 93106 USA Department of Electrical and Computer Engineering Princeton University Princeton New Jersey 08544 USA Department of Physics and Astronomy and Quantum Matter Institute University of British Columbia Vancouver BC Canada V6T 1Z1 Department of Physics University of Massachusetts Amherst Massachusetts 01003 USA Joint Center for Quantum Information and Computer Science NIST and University of Maryland College Park Maryland 20742 USA Institute for Physical Science and Technology University of Maryland College Park Maryland 20742 USA

Monitored quantum circuits exhibit entanglement transitions at certain measurement rates. Such a transition separates phases characterized by how much information an observer can learn from the measurement outcomes. We study SU(2)-symmetric monitored quantum circuits, using exact numerics and a mapping onto an effective statistical-mechanics model. Due to the symmetry's non-Abelian nature, measuring qubit pairs allows for nontrivial entanglement scaling even in the measurement-only limit. We find a transition between a volume-law entangled phase and a critical phase whose diffusive purification dynamics emerge from the non-Abelian symmetry. Additionally, we identify a “spin-sharpening transition.” Across the transition, the rate at which measurements reveal information about the total spin quantum number changes parametrically with system size.

关键词： Dynamical phase transitions Measurement-based quantum computing Open quantum systems Phase transitions quantum channels quantum computation quantum entanglement quantum gates

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Arbitrary coherent distributions in a programmable quantum walk

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Physical Review Research 2022年第2期4卷 023042-023042页

作者： Rong Zhang Ran Yang Jian Guo Chang-Wei Sun Yi-Chen Liu Heng Zhou Ping Xu Zhenda Xie Yan-Xiao Gong Shi-Ning Zhu National Laboratory of Solid State Microstructure School of Physics School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China College of Electronic and Optical Engineering Nanjing University of Posts and Telecommunication Nanjing 210023 China School of Information and Communication Engineering University of Electronic Science and Technology of China Chengdu 611731 China Institute for Quantum Information and State Key Laboratory of High Performance Computing College of Computing National University of Defense Technology Changsha 410073 China

The coherent superposition of position states in a quantum walk (QW) can be precisely engineered towards the desired distributions to meet the need of quantum information applications. The coherent distribution can make full use of quantum parallel in computation and simulation. Particularly, the uniform superposition provides the robust nonlocality, which has wide applications such as the generation of genuine multibit random numbers without postprocessing. We experimentally demonstrate that the rich dynamics featured with arbitrary coherent distributions can be obtained by introducing different sets of the time- and position-dependent operations. Such a QW is realized by a resource-constant and flexible optical circuit, in which the variable operation is executed based on a Sagnac interferometer in an intrinsically stable and precisely controlled way. Our results contribute to the practical realization of quantum-walk-based quantum computation, quantum simulations, and quantum information protocols.

关键词： quantum control quantum information architectures & platforms quantum protocols

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Hamiltonian phase error in resonantly driven CNOT gate above the fault-tolerant threshold

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npj quantum Information 2024年第1期10卷 1-9页

作者： Wu, Yi-Hsien Camenzind, Leon C. Noiri, Akito Takeda, Kenta Nakajima, Takashi Kobayashi, Takashi Chang, Chien-Yuan Sammak, Amir Scappucci, Giordano Goan, Hsi-Sheng Tarucha, Seigo Department of Physics National Taiwan University Taipei10617 Taiwan 2-1 Hirosawa Saitama Wako-shi351-0198 Japan RIKEN Center for Quantum Computing 2-1 Hirosawa Saitama Wako-shi351-0198 Japan Stieltjesweg 1 Delft2628 CK Netherlands QuTech and Kavli Institute of Nanoscience Delft University of Technology DelftPO Box 50462600 GA Netherlands Center of Quantum Science and Engineering National Taiwan University Taipei10617 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan

Because of their long coherence time and compatibility with industrial foundry processes, electron spin qubits are a promising platform for scalable quantum processors. A full-fledged quantum computer will need quantum error correction, which requires high-fidelity quantum gates. Analyzing and mitigating gate errors are useful to improve gate fidelity. Here, we demonstrate a simple yet reliable calibration procedure for a high-fidelity controlled-rotation gate in an exchange-always-on Silicon quantum processor, allowing operation above the fault-tolerance threshold of quantum error correction. We find that the fidelity of our uncalibrated controlled-rotation gate is limited by coherent errors in the form of controlled phases and present a method to measure and correct these phase errors. We then verify the improvement in our gate fidelities by randomized benchmark and gate-set tomography protocols. Finally, we use our phase correction protocol to implement a virtual, high-fidelity, controlled-phase gate. © 2024, The Author(s).

关键词： Magnetic moments

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Fermionic quantum approximate optimization algorithm

arXiv

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arXiv 2023年

作者： Yoshioka, Takuya Sasada, Keita Nakano, Yuichiro Fujii, Keisuke Strategic Technology Center TIS Inc. 2-2-1 Toyosu Koto-ku Tokyo135-0061 Japan Graduate School of Engineering Science Osaka University 1-3 Machikaneyama Osaka Toyonaka560-8531 Japan Center for Quantum Information and Quantum Biology Institute for Open and Transdisciplinary Research Initiatives Osaka Univrsity 1-2 Machikaneyama Osaka Toyonaka560-0043 Japan Center for Quantum Computing RIKEN 2-1 Hirosawa Saitama Wako351-0198 Japan

quantum computers are expected to accelerate solving combinatorial optimization problems, including algorithms such as Grover adaptive search and quantum approximate optimization algorithm (QAOA). However, many combinatorial optimization problems involve constraints which, when imposed as soft constraints in the cost function, can negatively impact the performance of the optimization algorithm. In this paper, we propose fermionic quantum approximate optimization algorithm (FQAOA) for solving combinatorial optimization problems with constraints. Specifically FQAOA tackle the constrains issue by using fermion particle number preservation to intrinsically impose them throughout QAOA. We provide a systematic guideline for designing the driver Hamiltonian for a given problem Hamiltonian with constraints. The initial state can be chosen to be a superposition of states satisfying the constraint and the ground state of the driver Hamiltonian. This property is important since FQAOA reduced to quantum adiabatic computation in the large limit of circuit depth p and improved performance, even for shallow circuits with optimizing the parameters starting from the fixed-angle determined by Trotterized quantum adiabatic evolution. We perform an extensive numerical simulation and demonstrates that proposed FQAOA provides substantial performance advantage against existing approaches in portfolio optimization problems. Furthermore, the Hamiltonian design guideline is useful not only for QAOA, but also Grover adaptive search and quantum phase estimation to solve combinatorial optimization problems with constraints. Since software tools for fermionic systems have been developed in quantum computational chemistry both for noisy intermediate-scale quantum computers and fault-tolerant quantum computers, FQAOA allows us to apply these tools for constrained combinatorial optimization problems. Copyright © 2023, The Authors. All rights reserved.

关键词： Hamiltonians

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QPanda3: A High-Performance Software-Hardware Collaborative Framework for Large-Scale quantum-Classical computing Integration

arXiv

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arXiv 2025年

作者： Zou, Tianrui Fang, Yuan Wang, Jing Dou, Menghan Fu, Jun Zhao, ZiQiang Zhao, ShuBin Yu, Lei Zhao, Dongyi Chen, Zhaoyun Guo, Guoping Origin Quantum Computing Company Limited Hefei China Anhui Engineering Research Center of Quantum Computing Hefei China Institute of Artificial Intelligence Hefei Comprehensive National Science Center Hefei China CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei China

QPanda3 is a high-performance quantum programming framework that enhances quantum computing efficiency through optimized circuit compilation, an advanced instruction stream format (OriginBIS), and hardware-aware execution strategies. These engineering optimizations significantly improve both processing speed and system performance, addressing key challenges in the NISQ era. A core innovation, OriginBIS, accelerates encoding speeds by up to 86.9× compared to OpenQASM 2.0, while decoding is 35.6× faster, leading to more efficient data handling, reduced memory overhead, and improved communication efficiency. This directly enhances the execution of quantum circuits, making large-scale quantum simulations more feasible. Comprehensive benchmarking demonstrates QPanda3’s superior performance: quantum circuit construction is 20.7× faster, execution speeds improve by 3.4×, and transpilation efficiency increases by 14.97× over Qiskit. Notably, in compiling a 118-qubit W-state circuit on a 2D-grid topology, QPanda3 achieves an unprecedented 869.9× speedup, underscoring its ability to handle complex quantum workloads at scale. By combining high-speed quantum processing with a modular and extensible software architecture, QPanda3 provides a practical bridge between today’s NISQ devices and future fault-tolerant quantum computing. It facilitates real-world applications in financial modeling, materials science, and combinatorial optimization, while its robust and scalable design supports industrial adoption and cloud-based deployment. © 2025, CC BY-NC-SA.

关键词： Qubits

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Impurity and dispersion effects on the linear magnetoresistance in the quantum limit

arXiv

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arXiv 2022年

作者： Li, Shuai Lu, Hai-Zhou Xie, X.C. Department of Physics Harbin Institute of Technology Harbin150001 China Shenzhen518055 China Shenzhen518045 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen518055 China International Quantum Academy Shenzhen518048 China International Center for Quantum Materials School of Physics Peking University Beijing100871 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Hefei National Laboratory Hefei230088 China

Magnetoresistance, that is, the change of the resistance with the magnetic field, is usually a quadratic function of the field strength. A linear magnetoresistance usually reveals extraordinary properties of a system. In the quantum limit where only the lowest Landau band is occupied, a quantum linear magnetoresistance was believed to be the signature of the Weyl fermions with 3D linear dispersion. Here, we comparatively investigate the quantum-limit magnetoresistance of systems with different band dispersions as well as different types of impurities. We find that the magnetoresistance can also be linear for the quadratic energy dispersion. We show that both longitudinal and transverse magnetoresistance can be linear if long-range-Gaussian-type impurities dominate, but Coulomb-type impurities can only induce linear transverse magnetoresistance. Moreover, we find a negative longitudinal magnetoresistance in massless Dirac fermions, regardless of the impurity type, as a result of the combined effect of the linear dispersion and the scattering mechanism. Our findings well explain some of the linear magnetoresistance observed in the experiments and provide insights to the understanding of quantum-limit magnetoresistance. Copyright © 2022, The Authors. All rights reserved.

关键词： Magnetoresistance

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Graph adversarial self-supervised learning 21

Graph adversarial self-supervised learning

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Proceedings of the 35th International Conference on Neural Information Processing Systems

作者： Longqi Yang Liangliang Zhang Wenjing Yang Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha China and Defense Innovation Institute Beijing China Institute of Systems Engineering AMS Beijing China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha China

ISBN: (纸本)9781713845393

This paper studies a long-standing problem of learning the representations of a whole graph without human supervision. The recent self-supervised learning methods train models to be invariant to the transformations (views) of the inputs. However, designing these views requires the experience of human experts. Inspired by adversarial training, we propose an adversarial self-supervised learning (GASSL) framework for learning unsupervised representations of graph data without any handcrafted views. GASSL automatically generates challenging views by adding perturbations to the input and are adversarially trained with respect to the encoder. Our method optimizes the min-max problem and utilizes a gradient accumulation strategy to accelerate the training process. Experimental on ten graph classification datasets show that the proposed approach is superior to state-of-the-art self-supervised learning baselines, which are competitive with supervised models.

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Angle-resolved magneto-chiral anisotropy in a non-centrosymmetric atomic layer superlattice

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Science Bulletin 2025年第9期70卷 1406-1409页

作者： Long Cheng Mingrui Bao Xue Zhang Jingxian Zhang Qun Yang Qiang Li Hui Cao Dawei Qiu Hui Li Guanglei Cheng Hua Zhou Jian-Min Zuo Xiaodong Zhou Jian Shen Zhifeng Zhu Wenbo Wang Xiaofang Zhai School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of ChinaHefei 230026China School of Information Science and Technology ShanghaiTech UniversityShanghai 201210China State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China X-ray Science Division Advanced Photon SourceArgonne National LaboratoryLemontIL 60439USA Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China Department of Materials Science and Engineering and Materials Research Laboratory University of Illinois Urbana–ChampaignUrbanaIL 61801USA ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China

Chirality is a widespread phenomenon in nature,where two non-superimposable enantiomers exist with one being the mirror image of the *** interplay between chirality and magnetism has recently drawn intensive interest in non-centrosymmetric magnetic materials absent of both spatial and time inversion symmetries[1].Among various chiral magnetic effects,the electrical manifestation of the magneto-chiral effect is crucial for both fundamental science and technological applications[2,3].The non-reciprocal resistance depending on the inner product of the magnetic field(H)and the current density U),termed the electrical magneto-chiral effect(eMChE),has recently been demonstrated in correlated oxides[4,5].

关键词： chiral magnetic effectsthe non reciprocal resistance EMCHE magnetism correlated oxides non centrosymmetric atomic layer superlattice chirality electrical magneto chiral effect

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Fiber-integrated microwave-to-optical quantum transducer

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Physical Review Applied 2023年第4期20卷 044031-044031页

作者： Wenfang Li Jinjin Du C. M. Wilson Michal Bajcsy Institute for Quantum Computing University of Waterloo 200 University Avenue West Waterloo Ontario N2L 3G1 Canada Okinawa Institute of Science and Technology Graduate University Onna Okinawa 904-0495 Japan Department of Electrical and Computer Engineering University of Waterloo 200 University Avenue West Waterloo Ontario N2L 3G1 Canada

We propose an on-chip fiber-based quantum transducer to convert microwave photons into optical-telecommunication-band photons. The device consists of a coplanar-waveguide microwave resonator and a pair of coupled optical cavities integrated into a rare-earth-doped fiber. The microwave resonator is formed by two aluminum strips deposited onto the cladding of the fiber, whose diameter has been etched down to approximately 8μm. We study the conversion process using the cavity electro-optic formalism for a system operating at liquid-helium temperature (around 4 K), as well as using a three-wave mixing approach for operation at millikelvin temperatures achievable in a dilution refrigerator. Both methods predict that unity conversion efficiency could be achievable with realistically achievable experimental parameters. The proposed device acts as a quantum transducer for coherent microwave-to-optical conversion, which has great promise for application in all-fiber integrated quantum devices for quantum information processing.

关键词： Integrated optics Light-matter interaction Optical quantum information processing quantum communication Optical fibers Transducers Microwave techniques Optical techniques

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