New features of entanglement dynamics with initial system-bath correlations

We investigate the influence of initial correlations between two qubits and a family of baths on the entanglement dynamics of these two qubits. We show that initial system-bath correlations can effectively avoid the occurrence of entanglement sudden death, and for the initial states with quantum correlations the entanglement between two qubits can be larger than its initial value. Significantly, we find that there exist initial states which we called entanglement preserving states, such that, although the state of the qubit subsystem evolves the entanglement of two qubits does not evolves at all.