Temperature-resistant generation of robust entanglement with blue-detuning driving and mechanical gain.

We present a proposal to generate robust optomechanical entanglement induced by the blue-detuning laser and the mechanical gain in a double-cavity optomechanical system. We show that the stability of the system can be obtained by introducing a cavity mode driven by the red-detuning laser in the blue-detuning regime. In contrast to the red-detuning regime, we find that the entanglement in the blue-detuning regime is extremely robust to temperature. The cavity mode driven by the blue-detuning laser can control indirectly the optomechanical entanglement between mechanical resonator and cavity mode driven by the red-detuning laser. Moreover, the entanglement between two cavity modes without direct coupling can also be achieved in our system. Although the entanglement is weak, it is robust to temperature, and meanwhile, the optomechanical entanglement is hardly affected by the temperature when the damping rate of the mechanical oscillator is close to zero. Furthermore, the entanglement amplification at high temperature can be achieved by adjusting the mechanical gain appropriately. Our proposal provides an efficient way to achieve robust optomechanical entanglement in the blue-detuning regime and entanglement amplification in optomechanical system with mechanical gain.