In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we describe the evolution of the Uhlmann quantum fidelity of a pair of two-mode Gaussian states, for a system consisting of two non-interacting bosonic modes embedded in two independent thermal environments. We take entangled squeezed thermal states as initial states of the considered system and describe the dependence of fidelity, which is fully determined by the covariance matrix, on time and temperatures of thermal reservoirs. We also present the explicit expression of the fidelity at infinity of time as a function of temperatures of the two reservoirs, squeezing parameter and average numbers of thermal photons, and show that quantum fidelity takes always only non-zero values.
展开▼
