Following the theoretical suggestion of Ref. [1,2], we present experimental results addressed to test restricted families of local realistic models, but without relying on the fair sampling assumption.
This note describes an algorithm for enumerating all the elements in a finite set based on uniformly random sampling from the set. This algorithm can be used for enumeration by fair sampling with quantum annealing. Our algorithm is based on a lemma of the coupon collector's problem and is an improved version of the algorithm described in arXiv:2007.08487 (2020). We provide a mathematical analysis and a numerical demonstration of our algorithm.
Bell violation with entangled photons, free of the coincidence-time loophole
在局部实在论的世界观中,物理性质是在测量之前定义的,并且与测量无关,没有任何物理影响可以比光速传播得更快。对贝尔不等式的适当的实验违反将表明,世界不能在局部实在论中描述。这样的实验通常需要额外的假设,这使得它们容易受到一些“漏洞”的影响。“最近的一个实验[Giustina et al,Nature,2013]违反了贝尔不等式,而不容易受到检测(或公平采样)漏洞的影响,因此不需要公平采样假设。本文分析了更为微妙的符合时间漏洞,提出并证明了两种不同的数据分析方法的有效性,这两种方法都是通用的,可用于脉冲和连续波实验。我们应用它们证明了上述实验违反了局部实在论,而不容易受到时间重合漏洞的影响,因此不需要相应的公平重合假设。
Sampling all ground states of a Hamiltonian with equal probability is a desired feature of a sampling algorithm, but recent studies indicate that common variants of transverse field quantum annealing sample the ground state subspace unfairly. In this note, we present perturbation theory arguments suggesting that this deficiency can be corrected by employing reverse annealing-inspired paths. We confirm that this conclusion holds in simulations of previously studied small instances with degeneracy, as well as larger instances on quantum annealing hardware.
We present a loophole-free violation of local realism using entangled photon pairs. We ensure that all relevant events in our Bell test are spacelike separated by placing the parties far enough apart and by using fast random number generators and high-speed polarization measurements. A high-quality polarization-entangled source of photons, combined with high-efficiency, low-noise, single-photon detectors, allows us to make measurements without requiring any fair-sampling assumptions. Using a hypothesis test, we compute p-values as small as $5.9\times 10^{-9}$ for our Bell violation while maint…
Recently, a group of experiments tested local realism with random choices prepared by humans. These various tests were subject to additional assumptions, which lead to loopholes in the interpretations of almost all of the experiments. Among these assumptions are fair sampling, no signaling, and faithful reproduction of a Bell-type quantum model. We examined the data from 9 of 13 experiments and analyzed occurring anomalies in view of the above assumptions. We conclude that further tests of local realism need better setup calibration to avoid apparent signaling or necessity of the complicated u…
Discarding undesirable measurement results in Bell experiments opens the detection loophole that prevents a conclusive demonstration of nonlocality. As closing the detection loophole represents a major technical challenge for many practical Bell experiments, it is customary to assume the so-called fair sampling assumption (FSA) that, in its original form, states that the collectively postselected statistics are a fair sample of the ideal statistics. Here, we analyze the FSA from the viewpoint of causal inference: We derive a causal structure that must be present in any causal model that faithf…
Fair sampling with temperature-targeted QAOA based on quantum-classical correspondence theory
Graduate School of Science and Technology, Keio University(庆应义塾大学理工学研究科);Department of Applied Physics and Physico-Informatics, Keio University(庆应义塾大学应用物理与物理信息学系);Keio University Sustainable Quantum Artificial Intelligence Center (KSQAIC), Keio University(庆应义塾大学可持续量子人工智能中心);Human Biology-Microbiome-Quantum Research Center (WPI-Bio2Q), Keio University(庆应义塾大学人类生物学-微生物组-量子研究中心);Green Computing System Research Organization, Waseda University(早稻田大学绿色计算系统研究组织)
Modern NISQ devices are subject to a variety of biases and sources of noise that degrade the solution quality of computations carried out on these devices. A natural question that arises in the NISQ era, is how fairly do these devices sample ground state solutions. To this end, we run five fair sampling problems (each with at least three ground state solutions) that are based both on quantum annealing and on the Grover Mixer-QAOA algorithm for gate-based NISQ hardware. In particular, we use seven IBM~Q devices, the Aspen-9 Rigetti device, the IonQ device, and three D-Wave quantum annealers. Fo…
The Greenberger-Horne-Zeilinger (GHZ) puzzle has been used to study quantum nonlocality and provide an all-or-nothing, no-go theorem for local hidden-variable models. Recent experiments using coincident-detected entangled photons prepared in a three-particle GHZ state have been used to test quantum nonlocality, but fail to rule out local realism due to a reliance on the fair-sampling hypothesis and insufficient detection efficiency. This paper describes a physically motivated local hidden-variable model based on amplitude-threshold detection that is capable of producing similar results. Detect…
Interpretation of Unfair Sampling in Quantum Annealing by Node Centrality
Graduate School of Information Science, Tohoku University(东北大学信息科学研究院);Sigma-i Co., Ltd.(Sigma-i有限公司);Department of Physics, Institute of Science Tokyo(东京科学大学物理系);Research and Education Institute for Semiconductors and Informatics, Kumamoto University(熊本大学半导体与信息学研究与教育学院)