Decrease of the decay rate of the entanglement of a system of two entangled qubits by increasing the temperature of the thermal bath

Abstract

We have investigated the effects of indirect coupling between a nonlinear system of two qubits, initially prepared in an entangled state, and a thermal bath. We obtained an analytical solution for this system that allowed us to analyze the effects of high temperature on the entanglement. We found a nonintuitive behavior: Higher thermal reservoir temperatures imply smaller decay rates of entanglement. The indirect coupling between the two-qubit system and a thermal bath, via a third qubit that is also a two-level system acting as a structured reservoir, it is capable of slowing down of the losses of entanglement, despite the destructive effects of the environment. This third qubit is responsible for substantially suppressing the decoherence effects on the degree of entanglement of the two-qubit system.