Decoherence dynamics of a general quadratic state in a thermal environment

Abstract

Building on our recently completed work [Chinese J. Phys. 94 (2025) 215], we extend the analysis to a general quadratic state and focus on its analytical evolution in a thermal environment, where it retains the same form as the input state throughout. We also investigate the mean photon number, photon counting distribution, and Wigner distribution function in the thermal environment. In addition, using the differential representation of the von Neumann entropy, we analytically and numerically study the entropy evolution of the quadratic state for thermal noise.