Macroscopic Limit of Quantum Systems

Classical physics is approached from quantum mechanics in the macroscopic limit. The technical device to achieve this goal is the quantum version of the central limit theorem, derived for an observable at a given time and for the time-dependent expectation value of the coordinate. The emergence of t...

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Bibliographic Details
Main Author: Janos Polonyi
Format: Article
Language:English
Published: MDPI AG 2021-08-01
Series:Universe
Subjects:
Online Access:https://www.mdpi.com/2218-1997/7/9/315
Description
Summary:Classical physics is approached from quantum mechanics in the macroscopic limit. The technical device to achieve this goal is the quantum version of the central limit theorem, derived for an observable at a given time and for the time-dependent expectation value of the coordinate. The emergence of the classical trajectory can be followed for the average of an observable over a large set of independent microscopical systems, and the deterministic classical laws can be recovered in all practical purposes, owing to the largeness of Avogadro’s number. This result refers to the observed system without considering the measuring apparatus. The emergence of a classical trajectory is followed qualitatively in Wilson’s cloud chamber.
ISSN:2218-1997