Different descriptions of open quantum system dynamics - master equations

Abstract

Any realistic physical system is unavoidably coupled to some external degrees of freedom and should then be treated as an open system. That is why the open, reduced quantum dynamics plays an important role also in quantum technology applications. In the study of the dynamics of an open quantum system it is well known that alternative approximated descriptions are often useful. Here we show that also equivalent exact evolution equations can be introduced, investigating a newly introduced link between time local and time non-local master equations [1, 2]. Though these equations are in principle equivalent as their solutions are the same reduced density operator, the knowledge of both can be beneficial. Our approach, based on the damping basis representation, give some insights into the occurrence of different dephasing channels in time local and time non-local master equations and the non-Markovianity property of the exact and the approximated reduced dynamics. [1] - N. Megier, A. Smirne, B. Vacchini, New J. Phys. 22: 083011, 2020 [2] - N. Megier, A. Smirne, B. Vacchini, Entropy 22(7): 796, 2020