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The formalism of classical and quantum mechanics on phase space leads to symplectic and Heisenberg group representations, respectively. The Wigner functions give a representation of the quantum system using classical variables. The…

Quantum Physics · Physics 2007-05-23 Ajay Patwardhan

In canonical gravity, covariance is implemented by brackets of hypersurface-deformation generators forming a Lie algebroid. Lie algebroid morphisms therefore allow one to relate different versions of the brackets that correspond to the same…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Martin Bojowald , Suddhasattwa Brahma , Umut Buyukcam , Fabio D'Ambrosio

By considering (non-relativistic) quantum mechanics as it is done in practice in particular in condensed-matter physics, it is argued that a deterministic, unitary time evolution within a chosen Hilbert space always has a limited scope,…

Quantum Physics · Physics 2017-10-03 Barbara Drossel

We consider a semi-classical approximation to the dynamics of a point particle in a noncommutative space. In this approximation, the noncommutativity of space coordinates is described by a Poisson bracket. For linear Poisson brackets, the…

High Energy Physics - Theory · Physics 2024-05-24 Vladislav Kupriyanov , Maxim Kurkov , Alexey Sharapov

In this paper a formalism for studying the dynamics of quantum systems coupled to classical spin environments is reviewed. The theory is based on generalized antisymmetric brackets and naturally predicts open-path off-diagonal geometric…

Quantum Physics · Physics 2016-10-21 Alessandro Sergi

Canonical transformations are ubiquitous in Hamiltonian mechanics, since they not only describe the fundamental invariance of the theory under phase-space reparameterisations, but also generate the dynamics of the system. In the first part…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-01 Julien Grain , Vincent Vennin

The transport of ultra-cold atoms in magneto-optical potentials provides a clean setting in which to investigate the distinct predictions of classical versus quantum dynamics for a system with coupled degrees of freedom. In this system,…

We revise the technique of semiclassical effective dynamics, in particular reexamining the evaluation of Poisson structure of the so-called central moments capturing quantum corrections, providing a systematic, pedagogical, and efficient…

General Relativity and Quantum Cosmology · Physics 2025-06-09 Maciej Kowalczyk , Tomasz Pawłowski

The key feature of a quantum spin coupled to a harmonic bath---a model dissipative quantum system---is competition between oscillator potential energy and spin tunneling rate. We show that these opposing tendencies cause environmental…

Quantum Physics · Physics 2014-03-21 Soumya Bera , Serge Florens , Harold U. Baranger , Nicolas Roch , Ahsan Nazir , Alex W. Chin

The statistical mechanics of quantum-classical systems with holonomic constraints is formulated rigorously by unifying the classical Dirac bracket and the quantum-classical bracket in matrix form. The resulting Dirac quantum-classical…

Quantum Physics · Physics 2016-09-08 Alessandro Sergi

We argue with claims of the paper [Agostini F., Caprara S. and Ciccotti G., Europhys. Lett. EPL, 78 (2007) Art. 30001, 6] that the quantum-classic bracket introduced in [arXiv:quant-ph/0506122] produces "artificial coupling" and has…

Quantum Physics · Physics 2010-05-18 Vladimir V. Kisil

We present a consistent framework of coupled classical and quantum dynamics. Our result allows us to overcome severe limitations of previous phenomenological approaches, like evolutions that do not preserve the positivity of quantum states…

Quantum Physics · Physics 2009-10-31 Lajos Diosi , Nicolas Gisin , Walter T. Strunz

One of the hardest problems to tackle in the dynamics of canonical approaches to quantum gravity is that of the Hamiltonian constraint. We investigate said problem in the context of formal geometric quantization. We study the implications…

General Relativity and Quantum Cosmology · Physics 2013-04-19 Vasudev Shyam

Bosonic quantum conversion systems can be modeled by many-particle single-mode Hamiltonians describing a conversion of $n$ molecules of type A into $m$ molecules of type B and vice versa. These Hamiltonians are analyzed in terms of…

Quantum Physics · Physics 2016-04-13 Eva-Maria Graefe , Hans Jürgen Korsch , Alexander Rush

We present three statistical descriptions for systems of classical particles and consider their extension to hybrid quantum-classical systems. The classical descriptions are ensembles on configuration space, ensembles on phase space, and a…

Quantum Physics · Physics 2024-08-13 Andrés Darío Bermúdez Manjarres , Marcel Reginatto , Sebastian Ulbricht

The Hamiltonian formulation plays the essential role in constructing the framework of modern physics. In this paper, a new form of canonical equations of Hamilton with the complete symmetry is obtained, which are valid not only for the…

Classical Physics · Physics 2012-12-11 Guo Liang , Qi Guo

The dynamics of hybrid systems -- i.e. ones in which classical and quantum degrees of freedom co-exist and interact -- feature both diffusion in the classical sector and decoherence in the quantum state. In this article, we will consider…

Quantum Physics · Physics 2025-10-10 Emanuele Panella

Classical mechanics is formulated in complex Hilbert space with the introduction of a commutative product of operators, an antisymmetric bracket, and a quasidensity operator. These are analogues of the star product, the Moyal bracket, and…

Quantum Physics · Physics 2017-02-23 A. J. Bracken

Extending earlier work(*), we examine the deformation of the canonical symplectic structure in a cotangent bundle $T^\star(\Q)$ by additional terms implying the Poisson non-commutativity of both configuration and momentum variables. In this…

Mathematical Physics · Physics 2008-11-26 F. J. Vanhecke , C. Sigaud , A. R. da Silva

Continuous observation of a quantum system yields a measurement record that faithfully reproduces the classically predicted trajectory provided that the measurement is sufficiently strong to localize the state in phase space but weak enough…

Quantum Physics · Physics 2007-05-23 Shohini Ghose , Paul Alsing , Ivan Deutsch , Tanmoy Bhattacharya , Salman Habib , Kurt Jacobs