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We analyze interrelation of quantum and classical entanglement. The latter notion is widely used in classical optic simulation of some quantum-like features of light. We criticize the common interpretation that "quantum nonlocality" is the…

Quantum Physics · Physics 2021-03-26 Andrei Khrennikov

Identical particles and entanglement are both fundamental components of quantum mechanics. However, when identical particles are condensed in a single spatial mode, the standard notions of entanglement, based on clearly identifiable…

Quantum Physics · Physics 2014-04-23 N. Killoran , M. Cramer , M. B. Plenio

We consider entanglement in a system of fixed number of identical particles. Since any operation should be symmetrized over all the identical particles and there is the precondition that the spatial wave functions overlap, the meaning of…

Quantum Physics · Physics 2009-11-07 Yu Shi

We report a quantum interference and imaging experiment which quantitatively demonstrates that Einstein-Podolsky-Rosen (EPR) type entangled two-photon states exhibit both momentum-momentum and position-position correlations, stronger than…

Quantum Physics · Physics 2009-11-10 Milena D'Angelo , Yoon-Ho Kim , Sergei P. Kulik , Yanhua Shih

The extended Bloch representation of quantum mechanics was recently derived to offer a (hidden-measurement) solution to the measurement problem. In this article we use it to investigate the geometry of superposition and entangled states,…

Quantum Physics · Physics 2017-01-02 Diederik Aerts , Massimiliano Sassoli de Bianchi

We show that the Cauchy-Schwarz inequality provides a simple yet general bound that limits the accuracy of light-matter theories which retain only finite numbers of material energy levels. A corollary is that unitary rotations within a…

Quantum Physics · Physics 2025-03-12 Daniel Eyles , Adam Stokes , Ahsan Nazir

Regular quasiprobabilities are introduced for the aim of characterizing quantum correlations of multimode radiation fields. Negativities of these quantum-correlation quasiprobabilities are necessary and sufficient for any quantum…

Quantum Physics · Physics 2013-03-15 E. Agudelo , J. Sperling , W. Vogel

We provide a general description of the phenomenon of entanglement in bipartite systems, as it manifests in micro and macro physical systems, as well as in human cognitive processes. We do so by observing that when genuine coincidence…

The violation of a Bell inequality is a striking demonstration of how quantum mechanics contradicts local realism. Although the original argument was presented with a pair of spin 1/2 particles, so far Bell inequalities have been shown to…

Quantum Physics · Physics 2019-10-30 D. K. Shin , B. M. Henson , S. S. Hodgman , T. Wasak , J. Chwedenczuk , A. G. Truscott

Phase-space distributions are widely applied in quantum optics to access the nonclassical features of radiations fields. In particular, the inability to interpret the Glauber-Sudarshan distribution in terms of a classical probability…

Quantum Physics · Physics 2016-07-25 J. Sperling

Experiments showing the violation of Bell inequalities have formed our belief that the world at its smallest is genuinely non-local. While many non-locality experiments use the first quantised picture, the physics of fields of…

Quantum Physics · Physics 2013-05-29 Libby Heaney , Janet Anders

In the context of bipartite bosonic systems, two notions of classicality of correlations can be defined: P-classicality, based on the properties of the Glauber-Sudarshan P-function; and C-classicality, based on the entropic quantum discord.…

Continuous variable entanglement is a manifestation of nonclassicality of quantum states. In this paper we attempt to analyze whether and under which conditions nonclassicality can be used as an entanglement criterion. We adopt the…

Quantum Physics · Physics 2009-05-15 Petr Marek , M. S. Kim , Jinhyoung Lee

We provide experimental evidence of quantum features in bi-partite states classified as entirely classical according to a conventional criterion based on the Glauber P-function but possessing non-zero Gaussian quantum discord. Their quantum…

The entanglement properties of mixed states are of great importance in the study of open quantum systems and quantum information science, but commonly used entanglement measures, such as negativity, can be difficult to apply or connect to…

Quantum Physics · Physics 2025-08-04 Nishaant Jacobus , Paul Brumer , Chern Chuang

Historically, the completeness of quantum theory has been questioned using the concept of bipartite continuous variable entanglement. The non-classical correlations (entanglement) between the two subsystems imply that the observables of one…

Quantum Gases · Physics 2011-12-21 C. Gross , H. Strobel , E. Nicklas , T. Zibold , N. Bar-Gill , G. Kurizki , M. K. Oberthaler

In this paper, we study some quantum properties of a superposition of displaced squeezed two-mode vacuum and single-photon states, such as the second-order correlation function, the Cauchy-Schwartz inequality, quadrature squeezing,…

Quantum Physics · Physics 2009-11-13 Faisal A. A. El-Orany , A-S. F. Obada , Zafer M. Asker , J. Perina

We prove a set of inequalities that interpolate the Cauchy-Schwarz inequality and the triangle inequality. Every nondecreasing, convex function with a concave derivative induces such an inequality. They hold in any metric space that…

Metric Geometry · Mathematics 2025-01-06 Christof Schötz

We present a mechanical proof of the Cauchy-Schwarz inequality in ACL2(r) and a formalisation of the necessary mathematics to undertake such a proof. This includes the formalisation of $\mathbb{R}^n$ as an inner product space. We also…

Logic in Computer Science · Computer Science 2018-10-11 Carl Kwan , Mark R. Greenstreet

A generalized Cauchy-Schwarz inequality is derived and applied to uncertainty relation in quantum mechanics. We see a modification in the uncertainty relation and minimum uncertainty wave packet.

Quantum Physics · Physics 2015-09-15 Vishnu M. Bannur