Study of Quantum Decoherence in a Finite System -- Three Schroedinger Cats and Crossing of Classical Orbits

TL;DR

This paper investigates quantum decoherence in finite systems like nuclei, demonstrating how a subsystem can become classical through coupling with other degrees of freedom, and explores its relation to classical orbit crossing.

Contribution

It shows that in a three-body quantum system, a degree of freedom can attain classicality via decoherence caused by other degrees of freedom, linking decoherence to classical orbit crossing.

Findings

A subsystem becomes classical through quantum decoherence in a finite system.

Coupling between degrees of freedom induces classicality in a nuclear model.

Quantum decoherence relates to crossing of classical orbits in the model.

Abstract

Nuclei are rather classical systems in a sense. In the old days, their phenomena were roughly explained in classical rules such as the liquid drop model. This fact may be understood that when we see an finite quantum many body system like nucleus, though which is a group of quantum mechanical particles, its any collective degree of freedom has any classicality. Getting a classicality does not depend on spatial scales of objects. It is made by a phenomenon called Quantum Decoherence. We have studied about Quantum Decoherence in a finite system as nucleus. In this paper, at the harmonic three body problem (3 Schroedinger cats), it is shown that one degree of freedom as a sub-system would get classicality because of the other two degrees of freedom. Therefore we can assume that a nuclear collective degree of freedom would get classicality when it couples with any other internal degrees of freedom. In this paper, we also note that there is some relationship between the Quantum Decoherence and Crossing of classical orbits in 3 Schroedinger cats model.