Classical and mixed classical-quantum systems from van Hove's unitary representation of contact transformations

Fuente: arXiv
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Autori principali: Reginatto, Marcel, Manjarres, Andrés Darío Bermúdez, Ulbricht, Sebastian
Natura: Preprint
Pubblicazione: 2025
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author Reginatto, Marcel
Manjarres, Andrés Darío Bermúdez
Ulbricht, Sebastian
author_facet Reginatto, Marcel
Manjarres, Andrés Darío Bermúdez
Ulbricht, Sebastian
contents 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 to develop a novel formulation of classical mechanics in Hilbert space. This formulation differs from the Koopman-von Neumann theory in many ways. Classical observables are represented by van Hove operators, which satisfy a commutation algebra isomorphic to the Poisson algebra of functions in phase space. Moreover, these operators are both observables and generators of transformations, which makes it unnecessary to introduce unobservable auxiliary operators as in the Koopman-von Neumann theory. In addition, for consistency with classical mechanics, a constraint must be imposed that fixes the phase of the wavefunction. The approach can be extended to hybrid mixed classical-quantum systems in Hilbert space. The formalism is applied to the measurement of a quantum two-level system (qubit) by a classical apparatus.
format Preprint
id arxiv_https___arxiv_org_abs_2503_02480
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Classical and mixed classical-quantum systems from van Hove's unitary representation of contact transformations
Reginatto, Marcel
Manjarres, Andrés Darío Bermúdez
Ulbricht, Sebastian
Quantum Physics
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 to develop a novel formulation of classical mechanics in Hilbert space. This formulation differs from the Koopman-von Neumann theory in many ways. Classical observables are represented by van Hove operators, which satisfy a commutation algebra isomorphic to the Poisson algebra of functions in phase space. Moreover, these operators are both observables and generators of transformations, which makes it unnecessary to introduce unobservable auxiliary operators as in the Koopman-von Neumann theory. In addition, for consistency with classical mechanics, a constraint must be imposed that fixes the phase of the wavefunction. The approach can be extended to hybrid mixed classical-quantum systems in Hilbert space. The formalism is applied to the measurement of a quantum two-level system (qubit) by a classical apparatus.
title Classical and mixed classical-quantum systems from van Hove's unitary representation of contact transformations
topic Quantum Physics
url https://arxiv.org/abs/2503.02480