A simple demonstration of Bell's theorem involving two observers and no probabilities or inequalities
P. K. Aravind
备注:
8 pages, 1 table, 4 figures (some in color).This is a much briefer version of the earlier paper (with an altered title!) that gives a tighter description of the main gedanken experiment and also eliminates some obscurities in its presentation. Sections 4-6 plus the appendix of the earlier version, which treat specialized topics that do not bear on the main theme, have now been eliminated
This paper describes a device, consisting of a central source and two widely separated detectors with six switch settings each, that provides a simple gedanken demonstration of Bell's theorem without relying on either statistical effects or the occurrence of rare events. The mechanism underlying the operation of the device is revealed for readers with a knowledge of quantum mechanics.
We show that it is possible to have arbitrarily long sequences of Alices and Bobs so every (Alice, Bob) pair violates a Bell inequality. We propose an experiment to observe this effect with two Alices and two Bobs.
There is currently much interest in the recycling of entangled systems, for use in quantum information protocols by sequential observers. In this work, we study the sequential generation of Bell nonlocality via recycling one or both components of two-qubit states. We first give a description of two-valued qubit measurements in terms of measurement bias, strength, and reversibility, and derive useful tradeoff relations between them. Then, we derive one-sided monogamy relations for unbiased observables, that strengthen the recent Conjecture in [S. Cheng {\it et al.}, Phys. Rev. A \textbf{104}, L…
Stronger two-observer all-versus-nothing violation of local realism
我们引入了一个两个观察者的全对无的贝尔定理的证明,它减少了所需的量子预测的数量从9 [A。Cabello,Phys. Rev. Lett. 87,010403(2001); Z.- B. Chen等人,物理修订版信函90,160408(2003)]到4,提供了大量的证据反对当地的现实主义,降低了检测效率的要求,一个决定性的实验测试贝尔定理,并导致贝尔不等式类似Mermin不等式三个观察者[N. D. Mermin,Phys. Rev. Lett. 65,1838(1990)],但只需要两个观察员。
Decoherence is an unavoidable phenomenon that results from the interaction of the system with its surroundings. The study of decoherence due to the relativistic effects has the fundamental importance. The Unruh effect is observed by the relativistically accelerator observer. The unruh effect acts as a quantum channel and we call it the Unruh Channel. The Unruh channel can be characterize by providing its Kraus representation. We consider the bipartite scheme in which the quantum information is shared between an inertial observer (Alice) and an accelerated observer (Rob) in the case of Dirac fi…
We give strong analytic and numerical evidence that, under mild measurement assumptions, two qubits cannot both be recycled to generate Bell nonlocality between multiple independent observers on each side. This is surprising, as under the same assumptions it is possible to recycle just one of the qubits an arbitrarily large number of times [P. J. Brown and R. Colbeck, Phys. Rev. Lett. 125, 090401 (2020)]. We derive corresponding 'one-sided monogamy relations' that rule out two-sided recycling for a wide range of parameters, based on a general tradeoff relation between the strengths and maximum…
"All versus nothing" inseparability for two observers
Bell定理的无不等式证明[A. Cabello,Phys. Rev. Lett. 86,1911(2001)]被公式化为Greenberger-Horne-Zeilinger类证明,只涉及两个观察者。一方面,这种新的方法使我们能够导出一个实验上可检验的贝尔不等式,而这个不等式是量子力学所违背的。另一方面,它导致了一个新的状态独立的证明的Kochen-Specker定理,并提供了一个更广泛的视角之间的关系,主要的证明无隐变量。
We investigate the scenario where an observer, Alice, shares a two-qubit state with an arbitrary number of observers, Bobs, via sequentially and independently recycling the qubit in possession of the first Bob. It is known that there exist entangled states which can be used to have an arbitrarily long sequence of Bobs who can violate the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality with the single Alice. We show that there exist entangled states that do not violate the Bell inequality and whose entanglement can be detected by an arbitrary number of Bobs by suitably choosing the entangleme…
Comment on `A scattering quantum circuit for measuring Bell's time inequality: a nuclear magnetic resonance demonstration using maximally mixed states'
Souza,Oliveira and Sarthour(SOS)最近的一篇论文报道了Leggett-Garg不等式(有时称为时间贝尔不等式)的实验违反。量子力学叠加的不等式测试:如果不等式被违反,那么宏观实在论标题下的一大类经典理论就不能解释动力学。LG不等式的实验测试被执行必要的所谓“非侵入性”测量的困难所困扰(对于宏观现实主义者来说,这将从感兴趣的系统中提取信息而不干扰它)。SOS认为,他们仍然通过将系统置于最大混合状态来实现这个困难的目标。据称,该系统在实验过程中没有受到任何扰动。不幸的是,对于持怀疑态度的宏观现实主义者来说,这种方法最终是无法令人信服的,因此SOS得出的结论是不合理的。
Exploiting the tension between the two dynamics of quantum theory (QT) in the Wigner's Friend thought experiment, we point out that the standard QT leads to inconsistency in observed probabilities of measurement outcomes between two super-observers - Wigner and his Student. To avoid such inconsistent predictions of QT, we hypothesize two distinct perspectives. The first one is "Absoluteness of measurement (AoM)," that is, any measurement process is an absolute event irrespective of other observers and yields a single outcome. The other is "Non-absoluteness of measurement (NoM)" as the negation…
We show that rejection of local realism in quantum mechanics can be tested by Bell-type inequalities for two observers and low-order moments of continuous and unbounded observables. We prove that one requires three observables for each observer for a maximally entangled state and two observables for a non-maximally entangled state and write down appropriate inequalities and show violation by quantum examples. Finding an example for quadratures or position and momentum is left as an open problem.
Multipartite Bell-Greenberger-Horne-Zeilinger nonclassicality from interwoven frustrated down-conversion
International Centre for Theory of Quantum Technologies, University of Gdansk(格但斯克大学国际量子技术理论中心);Centre for Quantum Technologies, National University of Singapore(新加坡国立大学量子技术中心);Institute of Theoretical Physics and Astrophysics, University of Gdańsk(格但斯克大学理论与天体物理研究所);Faculty of Physics, Ludwig Maximilian University(路德维希-马克西米利安大学物理学院);Institute of Theoretical and Applied Informatics, Polish Academy of Sciences(波兰科学院理论与应用信息学研究所)