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In this article, we study the problem of comparing mixed quantum states: given $n$ unknown mixed quantum states, can one determine whether they are identical or not with an unambiguous quantum measurement? We first study universal…

Quantum Physics · Physics 2015-05-18 Shengshi Pang , Shengjun Wu

In a recent paper [12], we discussed the serious inconsistency present within the operational and mathematical definition(s) of the notion of pure state. Continuing this analysis, in this work we attempt to address the role of 'purity' and…

Quantum Physics · Physics 2020-04-17 Christian de Ronde , César Massri

In this sequence of papers, noncommutative analysis is used to give a consistent axiomatic approach to a unified conceptual foundation of classical and quantum physics. The present Part I defines the concepts of observables, states and…

Quantum Physics · Physics 2007-05-23 Arnold Neumaier

Bounds analogous to entropic uncertainty relations allow one to design practical tests to detect quantum entanglement by a collective measurement performed on several copies of the state analyzed. This approach, initially worked out for…

Quantum Physics · Physics 2013-01-04 Łukasz Rudnicki , Zbigniew Puchała , Paweł Horodecki , Karol Życzkowski

Proposals for nonlinear extenstions of quantum mechanics are discussed. Two different concepts of "mixed state" for any nonlinear version of quantum theory are introduced: (i) >genuine mixture< corresponds to operational "mixing" of…

Quantum Physics · Physics 2012-12-07 Pavel Bona

Entangled states are in conflict with a general physical principle which expresses that a composite entity exists if and only if its components also exist, and the hypothesis that pure states represent the actuality of a physical entity,…

Quantum Physics · Physics 2023-03-01 Diederik Aerts , Massimiliano Sassoli de Bianchi

Experimental evidence, the heuristics of indistinguishability, and its logical inconsistency with quantum formalism all argue against the existence of a quantum mixture uncorrelated with the exterior, that is, argue for the postulate "The…

Quantum Physics · Physics 2007-05-23 K. A. Kirkpatrick

A crucial and problematical feature of quantum mechanics (QM) is nonobjectivity of properties. The ESR model restores objectivity reinterpreting quantum probabilities as conditional on detection and embodying the mathematical formalism of…

Quantum Physics · Physics 2015-03-13 Claudio Garola , Sandro Sozzo

There are several instances where quantum anomalies of continuous and discrete classical symmetries play an important role in fundamental physics. Examples come from chiral anomalies in the Standard Model of fundamental interactions and…

High Energy Physics - Theory · Physics 2012-02-14 A. P. Balachandran , Amilcar R. de Queiroz

In this article we extend results from our previous work [Bendersky, de la Torre, Senno, Figueira and Ac\'in, Phys. Rev. Lett. 116, 230406 (2016)] by providing a protocol to distinguish in finite time and with arbitrarily high success…

We introduce the notion of the mixed state projected ensemble (MSPE), a collection of mixed states describing a local region of a quantum many-body system, conditioned upon measurements of the complementary region which are incomplete. This…

Quantum Physics · Physics 2025-12-30 Xie-Hang Yu , Wen Wei Ho , Pavel Kos

We introduce the concept of a physical process that purifies a mixed quantum state, taken from a set of states, and investigate the conditions under which such a purification map exists. Here, a purification of a mixed quantum state is a…

Quantum Physics · Physics 2007-05-23 M. Kleinmann , H. Kampermann , T. Meyer , D. Bruss

The partial trace is commonly introduced in quantum mechanics as an algebraic operation used to define reduced states of composite systems. However, the probabilistic origin of this operation goes systematically unnoticed in the literature.…

Quantum Physics · Physics 2026-03-26 Andrés Macho Ortiz , Francisco Javier Fraile Peláez , José Capmany

As a consequence of the place ascribed to measurements in the postulates of quantum mechanics, if two differently prepared systems are described with the same density operator \r{ho}, they are said to be in the same quantum state. For more…

Quantum Physics · Physics 2024-10-18 Alain Deville , Yannick Deville

A new quantum mechanical notion -- Conditional Density Matrix -- is discussed and is applied to describe some physical processes. This notion is a natural generalization of von Neumann density matrix for such processes as divisions of…

Quantum Physics · Physics 2007-05-23 V. V. Belokurov , O. A. Khrustalev , V. A. Sadovnichy , O. D. Timofeevskaya

The persistence of sub-Planck structure in phase space with loss of coherence is demonstrated in a mixed state, which comprises two terms in the density matrix. Its utility in carrying out Heisenberg-limited measurement and quantum…

Quantum Physics · Physics 2018-06-05 Asmita Kumari , A. K. Pan , P. K. Panigrahi

The arguments of Cohen [Phys. Rev. A {\bf 60}, 80 (1999)] against the `ignorance interpretation' of mixed states are questioned. The physical arguments are shown to be inconsistent and the supporting example illustrates the opposite of the…

Quantum Physics · Physics 2009-10-31 Daniel R. Terno

The concept of a superposition is a revolutionary novelty introduced by Quantum Mechanics. If a system may be in any one of two pure states x and y, we must consider that it may also be in any one of many superpositions of x and y. An…

Quantum Physics · Physics 2008-04-07 Daniel Lehmann

This paper presents a new `partitional' approach to understanding or interpreting standard quantum mechanics (QM). The thesis is that the mathematics (not the physics) of QM is the Hilbert space version of the math of partitions on a set…

Quantum Physics · Physics 2023-04-20 David Ellerman

The concept of an injective affine embedding of the quantum states into a set of classical states, i.e., into the set of the probability measures on some measurable space, as well as its relation to statistically complete observables is…

Quantum Physics · Physics 2015-06-16 Werner Stulpe