Nonclassicality of single quantum excitation of a thermal field in thermal environments

TL;DR

This paper investigates the nonclassicality of single photon-added thermal states in thermal environments by analyzing the Wigner function's negativity, revealing a decay threshold dependent on the thermal channel's temperature.

Contribution

It demonstrates that the decay threshold for nonclassicality is universal for pure or mixed states with zero vacuum population, independent of initial thermal state temperature.

Findings

Wigner function negativity disappears after a threshold time $ au_c$.

Threshold time depends only on the thermal channel's temperature.

Universal behavior for pure and mixed nonclassical states with zero vacuum population.

Abstract

The nonclassicality of single photon-added thermal states in the thermal channel is investigated by exploring the volume of the negative part of the Wigner function. The Wigner functions become positive when the decay time exceeds a threshold value $\gamma{t}_c$, which only depends on the effective temperature or mean thermal photon number of the thermal channel, but not depends on the effective temperature of the initial thermal state. This phenomenon is similar with the case of single quantum excitation of classical coherent states in thermal channel. Furthermore, we firstly demonstrate $\gamma{t}_c$ is the same for arbitrary pure or mixed nonclassical optical fields with zero population in vacuum state. PACS numbers: 42.50.Dv, 03.65.Yz, 05.40.Ca