Evolution of nonclassicality of the quasi-Bell states for a strongly coupled qubit-oscillator system

TL;DR

This paper investigates how the nonclassical features of quasi-Bell states in a strongly coupled qubit-oscillator system evolve over time, using phase-space distributions and entropy measures to quantify nonclassicality.

Contribution

It provides a detailed analysis of the time evolution of nonclassicality in quasi-Bell states via phase-space distributions and entropy comparisons, under the adiabatic approximation.

Findings

Negativity of the Wigner function indicates nonclassicality.

Wigner entropy and Wehrl entropy offer insights into quantum state properties.

Nonclassicality varies dynamically with system evolution.

Abstract

Starting with the quasi-Bell states of the qubit-oscillator system, we obtain time evolution of the density matrix under the adiabatic approximation. The composite density matrix leads to, via partial tracing of the qubit degree of freedom, the reduced density matrix of the oscillator that is utilized to obtain the quasi-probability distributions such as Glauber-Sudarshan P function, Wigner W function and Husimi Q function. The negativity of the Wigner function acts as a measure of the nonclassicality of the state. The negativity becomes particularly relevant in understanding a comparison between the Wigner entropy with the Wehrl entropy, which are based on the W function and Q function, respectively.