Improving Entanglement Generation Using the Coherence of a Nonthermal Reservoir

The effect of environmental coherence on bipartite and tripartite quantum entanglements using quantum collision models is studied. In the collision model, an open quantum system of two qubits indirectly interacts with the reservoir via auxiliary qubits. The reservoir is modeled as a collection of initially uncorrelated qubits prepared in an identically nonthermal state. It is shown that the coherence of the nonthermal reservoir contributes to the generation and protection of entanglement. It is found that adding coherence to the initial state of the reservoir qubit can significantly enhance the steady-state entanglement of the system, and the presence of coherence in the reservoir allows steady-state entanglement to be obtained in a higher temperature region.