Exact dynamics of interacting qubits in a thermal environment: Results beyond the weak coupling limit

Abstract

We demonstrate an exact mapping of a class of models of two interacting qubits in thermal reservoirs to two separate problems of spin-boson-type systems. Based on this mapping, exact numerical simulations of the qubits dynamics can be performed, beyond the weak system-bath coupling limit and the Markovian approximation. Given the time evolution of the system population and coherences, we study as an application the dynamics of entanglement between the pair of qubits immersed in boson thermal baths, showing a rich phenomenology, including an intermediate oscillatory behavior, the entanglement sudden birth, sudden death and revival. We find that the occurrence of entanglement sudden death in this model depends on the portion of the zero and double excitation states in the subsystem initial state. In the long-time limit, analytic expressions are presented at weak system-bath coupling, for a range of relevant qubit parameters. © IOP Publishing and Deutsche Physikalische Gesellschaft.