Entanglement instability in the interaction of two qubits with a common non-Markovian environment

In this work we study the steady state entanglement between two qubits interacting asymetrically with a common non-Markovian environment. Depending on initial two-qubit state, asymmetry in couplings each qubit and environment may lead to enhanced of system, measured terms concurrence. Our results indicate that, if qubit-qubit interaction is also present, concurrence always favored by symmetric or anti-symmetric coupling configuration. Although finite, predicted be highly unstable regime as long larger than reservoir.