On detection of quasiclassical states

TL;DR

This paper introduces a criterion for identifying classical states in quantum systems based on observable expectation values, utilizing group theory to find cases where the criterion is exactly computable from a single operator's spectrum.

Contribution

It provides a new criterion for classicality of mixed quantum states and characterizes when this criterion can be exactly calculated using group representation theory.

Findings

Criterion for classicality based on expectation values

Identification of cases with exact computability from a single operator

Application of group representation theory to quantum state analysis

Abstract

We give a criterion of classicality for mixed states in terms of expectation values of a quantum observable. Using group representation theory we identify all cases when the criterion can be computed exactly in terms of the spectrum of a single operator.