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Loophole-free test of macroscopic realism via high-order correlations of measurement

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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

Tight bounds on depth-2 QAC-circuits computing parity

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arXiv 2025年

作者： Fenner, Stephen Grier, Daniel Padé, Daniel Thierauf, Thomas Computer Science and Engineering Department ColumbiaSC29208 United States Institute for Quantum Computing University of Waterloo WaterlooONN2L3G1 Canada Department of Engineering Computer Science and Psychology Ulm Germany

We show that the parity of more than three non-target input bits cannot be computed by QAC-circuits of depth-2, not even uncleanly, regardless of the number of ancilla qubits. This result is incomparable with other recent lower bounds on constant-depth QAC-circuits by Rosenthal [ICTS 2021,arXiv:2008.07470] and uses different techniques which may be of independent interest: 1. We show that all members of a certain class of multivariate polynomials are irreducible. The proof applies a technique of Shpilka & Volkovich [STOC 2008]. 2. We give a tight-in-some-sense characterization of when a multiqubit CZ gate creates or removes entanglement from the state it is applied to. The current paper strengthens an earlier version of the paper [arXiv:2005.12169]. © 2025, CC BY.

关键词： quantum entanglement

Quark masses and low-energy constants in the continuum from the tadpole-improved clover ensembles

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Physical Review D 2024年第5期109卷 054507-054507页

作者： Zhi-Cheng Hu Bo-Lun Hu Ji-Hao Wang Ming Gong Guoming Liu Liuming Liu Peng Sun Wei Sun Wei Wang Yi-Bo Yang Dian-Jun Zhao Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences School of Physical Sciences Beijing 100049 China CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Atomic and Subatomic Structure and Quantum Control (MOE) Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter Institute of Quantum Matter South China Normal University Guangzhou 510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Guangdong Provincial Key Laboratory of Nuclear Science Southern Nuclear Science Computing Center South China Normal University Guangzhou 510006 China University of Chinese Academy of Sciences Beijing 100049 China. INPAC Shanghai Key Laboratory for Particle Physics and Cosmology Key Laboratory for Particle Astrophysics and Cosmology (MOE) School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Southern Center for Nuclear-Science Theory (SCNT) Institute of Modern Physics Chinese Academy of Sciences Huizhou 516000 Guangdong Province China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study UCAS Hangzhou 310024 China International Centre for Theoretical Physics Asia-Pacific Beijing/Hangzhou 100049 China

We present the light-flavor quark masses and low-energy constants using the 2+1 flavor full-QCD ensembles with stout smeared-clover fermion action and Symanzik gauge action. Both the fermion and gauge actions are tadpole improved self-consistently. The simulations are performed on 11 ensembles at three lattice spacings a∈[0.05,0.11] fm, four spatial sizes L∈[2.5,5.1] fm, seven pion masses mπ∈[135,350] MeV, and several values of the strange quark mass. The quark mass is defined through the partially conserved axial current relation and renormalized to MS¯(2 GeV) through the intermediate regularization independent momentum subtraction scheme. The systematic uncertainty of using the symmetric momentum subtraction scheme is also included. Eventually, we predict mu=2.45(22)(20) MeV, md=4.74(11)(09) MeV, and ms=98.8(2.9)(4.7) MeV with the systematic uncertainties from lattice spacing determination, continuum extrapolation and renormalization constant included. We also obtain the chiral condensate Σ1/3=268.6(3.6)(0.7) MeV and the pion decay constant F=86.6(7)(1.4) MeV in the Nf=2 chiral limit, and the next-to-leading order low-energy constants ℓ3=2.43(54)(05) and ℓ4=4.322(75)(96).

关键词： Lattices Lattice QCD Lattice gauge theory

Arbitrary state creation via controlled measurement

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arXiv 2025年

作者： Zenchuk, Alexander I. Qi, Wentao Wu, Junde Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS Moscow reg. Chernogolovka142432 Russia Institute of Quantum Computing and Computer Theory School of Computer Science and Engineering Sun Yat-sen University Guangzhou510006 China School of Mathematical Sciences Zhejiang University Hangzhou310027 China

We propose the algorithm for creating an arbitrary pure quantum superposition state with required accuracy of encoding the amplitudes and phases of this state. The algorithm uses controlled measurement of the ancilla state to avoid the problem of small probability of detecting the required ancilla state. This algorithm can be a subroutine generating the required input state in various algorithms, in particular, in matrix-manipulation algorithms developed earlier. © 2025, CC BY.

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Universal algorithm for transforming Hamiltonian eigenvalues

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Physical Review Research 2025年第1期7卷 013331-013331页

作者： Tatsuki Odake Hlér Kristjánsson Philip Taranto Mio Murao Department of Physics Graduate School of Science The University of Tokyo Hongo 7-3-1 Bunkyo-ku Tokyo 113-0033 Japan Perimeter Institute for Theoretical Physics 31 Caroline Street North Waterloo Ontario N2L 2Y5 Canada Institute for Quantum Computing University of Waterloo 200 University Avenue West Waterloo Ontario N2L 3G1 Canada Department of Computer Science and Operations Research Université de Montréal Montréal Québec H3T 1J4 Canada Mila – Québec AI Institute Montréal Québec H2S 3H1 Canada Department of Physics & Astronomy University of Manchester Manchester M13 9PL United Kingdom Trans-Scale Quantum Science Institute The University of Tokyo Hongo 7-3-1 Bunkyo-ku Tokyo 113-0033 Japan

Manipulating Hamiltonians governing physical systems has found a broad range of applications, from quantum chemistry to semiconductor design. In this work, we provide a way of manipulating Hamiltonians, by transforming their eigenvalues while keeping their eigenstates unchanged. We develop a universal algorithm that deterministically implements any desired (suitably differentiable) function on the eigenvalues of any unknown Hamiltonian, whose positive-time and negative-time dynamics are given as a black box. Our algorithm uses correlated randomness to efficiently combine two subroutines—namely controlization and Fourier series simulation—exemplifying a general compilation procedure that we develop. The time complexity of our algorithm is significantly reduced via said compilation technique compared to a naïve concatenation of the subroutines and outperforms similar methods based on the quantum singular value transformation.

关键词： Subroutines

Characterization of exact one-query quantum algorithms

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Physical Review A 2020年第2期101卷 022325-022325页

作者： Weijiang Chen Zekun Ye Lvzhou Li Institute of Computer Science Theory School of Data and Computer Science Sun Yat-Sen University Guangzhou 510006 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen 518055 China Ministry of Education Key Laboratory of Machine Intelligence and Advanced Computing Sun Yat-Sen University Guangzhou 510006 China

The quantum query model is one of the most important models in quantum computing. Several well-known quantum algorithms are captured by this model, including the Deutsch-Jozsa algorithm, the Simon algorithm, the Grover algorithm, and others. In this paper, we characterize the computational power of exact one-query quantum algorithms. It is proved that a total Boolean function f:{0,1}n→{0,1} can be exactly computed by a one-query quantum algorithm if and only if f(x)=xi1 or xi1⊕xi2 (up to isomorphism). Note that, unlike most work in the literature based on the polynomial method, our proof does not resort to any knowledge about the polynomial degree of f.

关键词： quantum algorithms

Exploring Spatio-Temporal Dynamics for Enhanced Wind Turbine Condition Monitoring

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SSRN

SSRN 2023年

作者： Miao, Qiucheng Wang, Dandan Xia, Zongji Xu, Chuanfu Zhan, Jun Wu, Chengkun Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Hunan Changsha410005 China Huawei Technologies Co. Ltd. Guangdong Dongguan523429 China Extended Energy Big Data and Strategy Research Center Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences Shandong Qingdao266101 China

Efficient wind power cluster management and sustainable industry development require an optimized maintenance approach integrating condition monitoring. However, the intricate spatiotemporal correlations and non-stationarity of the data continue to pose significant challenges in extracting valuable insights from the supervisory control and data acquisition (SCADA) system. Hence, this paper proposes a novel approach for Dynamically Fusing Spatio-Temporal information with Difference Excitation (DFST-DE) in wind power systems' condition monitoring. First, it extracts spatial dependencies by integrating sparse graph with Gumbel Softmax regularization, and incorporates temporal information using a hybrid adaptive self-attention mechanism, which captures comprehensive spatiotemporal correlations. Second, it proposes a Spatio-Temporal Difference Excitation module to mitigate non-stationarity in time series data by smoothing trend changes. The proposed DFST-DE approach achieves superior performance by effectively fusing spatial, temporal and excitation information. Finally, it optimizes anomaly detection accuracy and efficiency by dynamically adjusting the threshold based on anomaly score statistics. Experimental results on real-world wind farm datasets demonstrate that the proposed approach outperforms other established methods in detecting early abnormal conditions in wind turbines. © 2023, The Authors. All rights reserved.

关键词： Condition monitoring

Non-Abelian symmetry can increase entanglement entropy

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arXiv 2022年

作者： Majidy, Shayan Lasek, Aleksander Huse, David A. Halpern, Nicole Yunger Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Perimeter Institute for Theoretical Physics WaterlooONN2L 2Y5 Canada Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Department of Physics Princeton University PrincetonNJ08544 United States Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States

The pillars of quantum theory include entanglement and operators’ failure to commute. The Page curve quantifies the bipartite entanglement of a many-body system in a random pure state. This entanglement is known to decrease if one constrains extensive observables that commute with each other (Abelian "charges"). Non-Abelian charges, which fail to commute with each other, are of current interest in quantum thermodynamics. For example, noncommuting charges were shown to reduce entropy-production rates and may enhance finite-size deviations from eigenstate thermalization. Bridging quantum thermodynamics to many-body physics, we quantify the effects of charges’ noncommutation—of a symmetry’s non-Abelian nature—on Page curves. First, we construct two models that are closely analogous but differ in whether their charges commute. We show analytically and numerically that the noncommuting-charge case has more entanglement. Hence charges’ noncommutation can promote entanglement. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum entanglement

Measuring bipartite spin correlations of lattice-trapped dipolar atoms

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arXiv 2024年

作者： Alaoui, Youssef Aziz Muleady, Sean R. Chaparro, Edwin Trifa, Youssef Rey, Ana Maria Roscilde, Tommaso Laburthe-Tolra, Bruno Vernac, Laurent Université Sorbonne Paris Nord Laboratoire de Physique des Lasers VilletaneuseF-93430 France CNRS UMR 7538 LPL VilletaneuseF-93430 France JILA NIST Department of Physics University of Colorado Boulder United States Center for Theory of Quantum Matter University of Colorado BoulderCO80309 United States Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Joint Quantum Institute NIST University of Maryland College ParkMD20742 United States Univ Lyon Ens de Lyon CNRS Laboratoire de Physique LyonF-69342 France

We demonstrate a bipartition technique using a super-lattice architecture to access correlations between alternating planes of a mesoscopic array of spin-3 chromium atoms trapped in a 3D optical lattice. Using this method, we observe that out-of-equilibrium dynamics driven by long-range dipolar interactions lead to spin anti-correlations between the two spatially separated subsystems. Our bipartite measurements reveal a subtle interplay between the anisotropy of the 3D dipolar interactions and that of the lattice structure, without requiring single-site addressing. We compare our results to theoretical predictions based on a truncated cumulant expansion and a new cluster semi-classical method that we use to investigate correlations at the microscopic scale. Comparison with a high-temperature analytical model reveals quantum thermalization at a high negative spin temperature. © 2024, CC BY.

关键词： Optical lattices