Decay of Gaussian correlations in local thermal reservoirs
Paulina Marian, Iulia Ghiu, Tudor A. Marian · Physica Scripta · 2015
In this paper we examine the decay of quantum correlations for the radiation field in a two-mode squeezed thermal state in contact with local thermal reservoirs. Two measures of the evolving quantum correlations between the modes are compared: the entanglement of formation and the quantum discord. We derive analytic expressions of the entanglement-death time in two special cases: when the reservoirs for each mode are identical, as well as when a single reservoir acts on the first mode only. In the latter configuration, we show that all the pure Gaussian states lose their entanglement at the same time, determined solely by the field-reservoir coupling. Also investigated is the evolution of the Gaussian quantum discord for the same choices of thermal baths. We notice that the discord can increase in time above its initial value in a special situation, namely, when the input state is mixed, and local measurements are performed on the attenuated mode. This enhancement of discord is stronger for zero-temperature reservoirs and increases with the input degree of mixing.