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It is shown that the the quantum phase space distributions corresponding to a density operator $\rho$ can be expressed, in thermofield dynamics, as overlaps between the state $\mid \rho >$ and "thermal" coherent states. The usefulness of…

Quantum Physics · Physics 2008-11-26 S. Chaturvedi , V. Srinivasan , G. S. Agarwal

A generalization of canonical quantization which maps a dynamical operator to a dynamical superoperator is suggested. Weyl quantization of dynamical operator, which cannot be represented as Poisson bracket with some function, is considered.…

Quantum Physics · Physics 2009-11-10 Vasily E. Tarasov

We discuss a model of repeated measurements of position in a quantum system which is monitored for a finite amount of time with a finite instrumental error. In this framework we recover the optimum monitoring of a harmonic oscillator…

Quantum Physics · Physics 2009-10-30 Michael B. Mensky , Roberto Onofrio , Carlo Presilla

In this work, the definition of the density operator on quantum states in Hilbert spaces and some of its aspects relevant in thermodynamics and information-theoretical entropy calculations are given. In this framework, a physical model…

Mathematical Physics · Physics 2017-09-25 Isiaka Aremua , Mahouton Norbert Hounkonnou , Ezinvi Baloitcha

In our previous papers we were interested in making a reconstruction of quantum mechanics according to classical mechanics. In this paper we suspend this program for a while and turn our attention to a theme in the frontier of quantum…

Quantum Physics · Physics 2007-05-23 L. S. F. Olavo

This manuscript explores a variational quantum formulation for nonlinear elasticity problems arising from hyperelastic material models, targeting near term noisy intermediate scale quantum (NISQ) devices. The approach leverages the…

Quantum Physics · Physics 2026-05-29 Uditnarayan Kouskiya , Caglar Oskay

We investigate the representations of the solutions to Maxwell's equations based on the combination of hypercomplex function-theoretical methods with quantum mechanical methods. Our approach provides us with a characterization for the…

Mathematical Physics · Physics 2011-03-02 Denis Constales , Nelson Faustino , Soeren Krausshar

Quantum chemistry is a near-term application for quantum computers. This application may be facilitated by variational quantum-classical algorithms (VQCAs), although a concern for VQCAs is the large number of measurements needed for…

Quantum Physics · Physics 2020-04-15 Andrew Arrasmith , Lukasz Cincio , Rolando D. Somma , Patrick J. Coles

The paper is devoted to integral quantization, a procedure based on operator-valued measure and resolution of the identity. We insist on covariance properties in the important case where group representation theory is involved. We also…

Quantum Physics · Physics 2019-11-06 Jean Pierre Gazeau , Herve Bergeron

Gabor analysis is one of the most common instances of time-frequency signal analysis. Choosing a suitable window for the Gabor transform of a signal is often a challenge for practical applications, in particular in audio signal processing.…

Numerical Analysis · Computer Science 2013-11-13 Benjamin Ricaud , Guillaume Stempfel , Bruno Torrésani , Christoph Wiesmeyr , Hélène Lachambre , Darian Onchis

Non-Markovian quantum state diffusion provides a wavefunction-based framework for modeling open quantum systems. In this work, we introduce a novel machine learning approach based on an operator construction algorithm. This algorithm…

Quantum Physics · Physics 2025-09-03 Jiaji Zhang , Carlos L. Benavides-Riveros , Lipeng Chen

We investigate time operators in the context of quantum time crystals in ring systems. A generalized commutation relation called the generalized weak Weyl relation is used to derive a class of self-adjoint time operators for ring systems…

Quantum Physics · Physics 2019-06-25 K. Nakatsugawa , T. Fujii , A. Saxena , S. Tanda

We address the problem of integrating operator equations concomitant with the dynamics of non autonomous quantum systems by taking advantage of the use of time-dependent canonical transformations. In particular, we proceed to a discussion…

Quantum Physics · Physics 2015-10-26 Mariagiovanna Gianfreda , Giulio Landolfi

We provide the most general forms of covariant and normalized time operators and their probability densities, with applications to quantum clocks, the time of arrival, and Lyapunov quantum operators. Examples are discussed of the profusion…

Quantum Physics · Physics 2015-05-19 G. C. Hegerfeldt , J. G. Muga , J. Muñoz

This work represents a first systematic attempt to create a common ground for semi-classical and time-frequency analysis. These two different areas combined together provide interesting outcomes in terms of Schr\"odinger type equations.…

Mathematical Physics · Physics 2018-01-17 Elena Cordero , Maurice de Gosson , Fabio Nicola

The Wigner-Weyl transform and phase space formulation of a density matrix approach are applied to a non-Hermitian model which is quadratic in positions and momenta. We show that in the presence of a quantum environment or reservoir, mean…

Quantum Physics · Physics 2019-10-09 Ludmila Praxmeyer , Konstantin G. Zloshchastiev

The focus of this work is a correspondence between the Hilbert space operators on one hand, and doubly periodic generalized functions on the other. The linear map that implements it, referred to as the Q-transform, enables a direct…

Quantum Physics · Physics 2017-08-04 Artur Sowa

We present a measure of quantum coherence by employing the concept of noncommutativity of operators in quantum mechanics. We analyse the behaviour of this noncommutative coherence and underline its similarities and differences with the…

Quantum Physics · Physics 2020-04-06 Shubhalakshmi S , Ujjwal Sen

We use quantum harmonic analysis for densely defined operators to provide a simplified proof of the Berger-Coburn theorem for boundedness of Toeplitz operators. In addition, we revisit compactness and Schatten-class membership of densely…

Functional Analysis · Mathematics 2025-08-20 Vishwa Dewage , Mishko Mitkovski

Quantum algorithms for diverse problems, including search and optimization problems, require the implementation of a reflection operator over a target state. Commonly, such reflections are approximately implemented using phase estimation.…

Quantum Physics · Physics 2018-03-08 Anirban Narayan Chowdhury , Yigit Subasi , Rolando D. Somma