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Quantum mechanical weak values of projection operators have been used to answer which-way questions, e.g. to trace which arms in a multiple Mach-Zehnder setup a particle may have traversed from a given initial to a prescribed final state. I…

Quantum Physics · Physics 2017-03-08 B. E. Y. Svensson

Five objections to the conventional arguments underlying the EPR \enquote{paradox} are presented. It is shown that for entangled subsystems the formation of the post-measurement state necessarily involves local interactions affecting both…

General Physics · Physics 2026-01-09 N. O. Chudak , O. S. Potiienko , I. V. Sharph , V. P. Smolyar

Quantum paradoxes show that quantum statistics can exceed the limits of positive joint probabilities for physical properties that cannot be measured jointly. It is therefore impossible to describe the relations between the different…

Quantum Physics · Physics 2015-06-24 Holger F. Hofmann

Statistical paradoxes such as the Hardy paradox and the enhancement of phase estimation via post-selection both draw upon the same non-classical features of quantum statistics described by non-positive quasi-probabilities. In this paper, we…

Quantum Physics · Physics 2026-01-29 Ming Ji , Yuxiang Yang , Holger F. Hofmann

Hardy's paradox was originally presented as a demonstration, without inequalities, of the incompatibility between quantum mechanics and the hypothesis of local causality. Equipped with newly developed tools that allow for a quantitative…

Quantum Physics · Physics 2020-02-19 N. G. Engelbert , R. M. Angelo

Weak values are usually associated with weak measurements of an observable on a pre- and post-selected ensemble. We show that more generally, weak values are proportional to the correlation between two pointers in a successive measurement.…

Quantum Physics · Physics 2009-08-03 Lars M. Johansen , Pier A. Mello

Eighty years ago Einstein demonstrated that a particular interpretation of the reduction of wave function led to a paradox and that this paradox disappeared if statistical interpretation of quantum mechanics was adopted. According to the…

Quantum Physics · Physics 2016-04-20 Marian Kupczynski

As with a Bell inequality, Hardy's paradox manifests a contradiction between the prediction given by quantum theory and local-hidden variable theories. In this work, we give two generalizations of Hardy's arguments for manifesting such a…

Quantum Physics · Physics 2024-04-10 Kai-Siang Chen , Shiladitya Mal , Gelo Noel M. Tabia , Yeong-Cherng Liang

Hardy's paradox (equivalently, Hardy's non-locality or Hardy's test) [\href{https://link.aps.org/doi/10.1103/PhysRevLett.68.2981}{L. Hardy, Phys. Rev. Lett. \textbf{68}, 2981 (1992)}] is used to show non-locality without inequalities and it…

Quantum Physics · Physics 2021-02-25 Soumya Das , Goutam Paul

We propose partial measurements as a conceptual tool to understand how to operate with counterfactual claims in quantum physics. Indeed, unlike standard von Neumann measurements, partial measurements can be reversed probabilistically. We…

Quantum Physics · Physics 2011-05-30 G. S. Paraoanu

In the present Note it is shown that Hardy thought experiment does not lead to any paradox and its explanation can be made by using quantum mechanical methods, without the need of weak measurements theories. The confusion arising about this…

Quantum Physics · Physics 2012-11-21 Y. Ben-Aryeh

A large literature has grown up around the proposed use of 'weak measurements' (i.e., unsharp measurements followed by post-selection) to allegedly provide information about hidden ontological features of quantum systems. This paper…

Quantum Physics · Physics 2017-05-16 R. E. Kastner

Characterizing high-dimensional entangled states is of crucial importance in quantum information science and technology. Recent theoretical progress has been made to extend the Hardy's paradox into a general scenario with multisetting…

Optics · Physics 2020-05-27 Dongkai Zhang , Xiaodong Qiu , Tianlong Ma , Wuhong Zhang , Lixiang Chen

We study the outcomes in a general measurement with postselection, and derive upper bounds for the pointer readings in weak measurement. Using the idea of weak measurement, we study Hardy's gedanken experiment and show how the "negative…

Quantum Physics · Physics 2015-06-12 Xuanmin Zhu , Qun Wei , Quanhui Liu , Shengjun Wu

Bipartite quantum entangled systems can exhibit measurement correlations that violate Bell inequalities, revealing the profoundly counter-intuitive nature of the physical universe. These correlations reflect the impossibility of…

Quantum Physics · Physics 2015-02-02 B. L. Higgins , M. S. Palsson , G. Y. Xiang , H. M. Wiseman , G. J. Pryde

A Hardy-like version of the quantum pigeonhole paradox is proposed, which can also be considered as a special kind of Hardy's paradox. Besides an example induced from the minimal system, a general construction of this paradox from an…

Quantum Physics · Physics 2022-04-13 Weidong Tang

Nonlocality can be studied through different approaches, such as Bell's inequalities, and it can be found in numerous quantum states, including GHZ states or graph states. Hardy's paradox, or Hardy-type nonlocality, provides a way to…

Quantum Physics · Physics 2026-01-09 Duc Manh Doan , Hung Q. Nguyen

Quantum mechanics represents one of the greatest triumphs of human intellect and, undoubtedly, is the most successful physical theory we have to date. However, since its foundation about a century ago, it has been uninterruptedly the center…

Quantum Physics · Physics 2016-04-08 Andrea Aiello , J. P. Woerdman

The Einstein-Podolsky-Rosen (EPR) paradox was presented as an argument that quantum mechanics is an incomplete description of physical reality. However, the premises on which the argument is based are falsifiable by Bell experiments. In…

Quantum Physics · Physics 2024-12-03 C. McGuigan , R. Y. Teh , P. D. Drummond , M. D Reid

Recent experiments have perfectly verified the fact that quantum correlations between two entangled particles are stronger than any classical, local pre-quantum worldview allows. This is famously called the EPR paradox first conceived as a…

History and Philosophy of Physics · Physics 2016-04-25 David Weinbaum