Thermal Vacuum State Corresponding to Displaced Thermal Optical Fields Density Operator and Its Applications

Abstract

The heart of the light field theory at finite temperatures is the introduce of a thermal vacuum state, which is also the basis for studying the statistical properties of quantum light fields. Based on Takahashi and Umezawa's thermal chaotic field dynamics theory (TFD), this paper introduces a " fictitious mode" to represent the degrees of freedom of the thermal environment, then the thermal vacuum of the displaced thermal state (DTS) is proposed and constructed by the integration within an ordered product (IWOP) in the extended space, and we obtained the expected value of the photon number, fluctuation, second-order coherence, Wigner function. Finally, it is found that the photon number of the system is decreased at a rate of \(\kappa t\) due to the interaction of the DTS with the surrounding thermal environment by calculating the photon number diffusion.