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Modal interpretations constitute a particular approach to associating dynamical variables with physical systems in quantum mechanics. Given the `quantum logical' constraints that are typically adopted by such interpretations, only certain…

Quantum Physics · Physics 2007-05-23 R. W. Spekkens , J. E. Sipe

In many a traditional physics textbook, a quantum measurement is defined as a projective measurement represented by a Hermitian operator. In quantum information theory, however, the concept of a measurement is dealt with in complete…

Quantum Physics · Physics 2015-11-06 Ravi Kunjwal , Chris Heunen , Tobias Fritz

In this paper we review some properties of fuzzy observables, mainly as realized by commutative positive operator valued measures. In this context we discuss two representation theorems for commutative positive operator valued measures in…

Quantum Physics · Physics 2009-07-01 S. Twareque Ali , Claudio Carmeli , Teiko Heinosaari , Alessandro Toigo

This note is devoted to some foundational aspects of quantum mechanics (QM) related to quantum information (QI) theory, especially quantum teleportation and ``one way quantum computing.'' We emphasize the role of the projection postulate…

Quantum Physics · Physics 2010-11-30 Andrei Khrennikov

Quantum coherence is a fundamental feature of quantum mechanics and an underlying requirement for most quantum information tasks. In the resource theory of coherence, incoherent states are diagonal with respect to a fixed orthonormal basis,…

Quantum Physics · Physics 2019-09-18 Felix Bischof , Hermann Kampermann , Dagmar Bruß

The coexistence relation of quantum effects is a fundamental structure, describing those pairs of experimental events that can be implemented in a single setup. Only in the simplest case of qubit effects an analytic characterization of…

Quantum Physics · Physics 2014-06-06 Teiko Heinosaari , Jukka Kiukas , Daniel Reitzner

Let $\mathcal{M}\subseteq\mathcal{B}\left( \mathcal{H}\right) $ be a countable decomposable properly infinite von Neumann algebra with a faithful normal semifinite tracial weight $\tau$ where $\mathcal{B}\left( \mathcal{H}\right) $ is the…

Operator Algebras · Mathematics 2021-11-08 Xiongfeng Zhan , Yifei Ruan , Henanbei Huang , Qihui Li

Descriptions of classical mechanics in Hilbert space go back to the work of Koopman and von Neumann in the 1930s. Decades later, van Hove derived a unitary representation of the group of contact transformations which recently has been used…

Quantum Physics · Physics 2025-04-02 Marcel Reginatto , Andrés Darío Bermúdez Manjarres , Sebastian Ulbricht

We show that a partition of the unity (or POVM) on a Hilbert space that is almost orthogonal is close to an orthogonal POVM in the same von Neumann algebra. This generalizes to infinite dimension previous results in matrix algebras by…

Operator Algebras · Mathematics 2022-01-12 Mikael de la Salle

An analytically derived 'integral operator' approach is introduced to estimate the expectation value of a quantum operator for an evolving state weighted with an exponential function. This allows to compute quantities useful in Nuclear…

Quantum Physics · Physics 2017-05-16 Simone Sturniolo

We consider positive operator valued measures whose image is the bounded operators acting on an infinite-dimensional Hilbert space, and we relax, when possible, the usual assumption of positivity of the operator valued measure seen in the…

Functional Analysis · Mathematics 2019-10-31 Darian McLaren , Sarah Plosker , Christopher Ramsey

We derive a measurement operator corresponding to a quantum nondemolition (QND) measurement of an atomic ensemble. The quantum measurement operator takes the form of a positive operator valued measure (POVM) and is valid for arbitrary…

This article presents a full operator analytical method for studying the quadratic nonlinear interactions in quantum optomechanics. The method is based on the application of higher-order operators, using a six-dimensional basis of second…

Quantum Physics · Physics 2018-11-13 Sina Khorasani

A multiple operator integral (MOI) is an indispensable tool in several branches of noncommutative analysis. However, there are substantial technical issues with the existing literature on the "separation of variables" approach to defining…

Operator Algebras · Mathematics 2023-12-27 Evangelos A. Nikitopoulos

Relativizing an idea from multiplicity theory, we say that an element x of a von Neumann algebra M is n-divisible if (W*(x)' cap M) unitally contains a factor of type I_n. We decide the density of the n-divisible operators, for various n,…

Operator Algebras · Mathematics 2008-06-09 David Sherman

Most modern classical processors support so-called von Neumann architecture with program and data registers. In present work is revisited similar approach to models of quantum processors. Deterministic programmable quantum gate arrays are…

Quantum Physics · Physics 2010-05-11 Alexander Yu. Vlasov

Quantum coherence is a fundamental feature of quantum physics and plays a significant role in quantum information processing. By generalizing the resource theory of coherence from von Neumann measurements to positive operator-valued…

Quantum Physics · Physics 2023-05-12 Meng-Li Guo , Jin-Min Liang , Bo Li , Shao-Ming Fei , Zhi-Xi Wang

Based on a recent proof of free choices in linking equations to the experiments they describe, I clarify relations among some purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and…

Quantum Physics · Physics 2014-09-15 John M. Myers

Examples are given of non-Hermitian Hamiltonian operators which have a real spectrum. Some of the investigated operators are expressed in terms of the generators of the Weil-Heisenberg algebra. It is argued that the existence of an…

Quantum Physics · Physics 2009-09-29 João da Providência , Natália Bebiano , João Pinheiro da Providência

This article introduces operator on operator regression in quantum probability. Here in the regression model, the response and the independent variables are certain operator valued observables, and they are linearly associated with unknown…

Methodology · Statistics 2024-08-02 Suprio Bhar , Subhra Sankar Dhar , Soumalya Joardar