Enhancement of mechanical entanglement in hybrid optomechanical system

We present a theoretical scheme for the enhancement of entanglement between the two distant mechanical resonators in a hybrid optomechanical system which is composed of a single-mode optomechanical cavity with an atomic ensemble of two-level atoms and two mechanical resonators coupled via Coulomb field. Our results show that the atomic detuning, collective atomic coupling and Coulomb interaction play a vital role in obtaining the enhanced entanglement between the two distant mechanical resonators. We can interplay these controlling parameters to obtain optimal entanglement for the system. Interestingly, the numerical simulation result reveals that such bi-partite entanglement persists for bath temperature up to 600 K. In the end, we show that the system's interaction with the atomic ensemble lead to an enhanced entanglement spectrum, which is robust against bath temperature as well. The present scheme will open new perspectives in constructing entanglement between two distant resonators and helpful to realize quantum memories for the continuous-variable quantum information processing.