A Quantum Optomechanical Transistor Based on a Cavity-Optomechanical   System
  We theoretically propose a scheme to realize an all-optically controlled quantum optomechanical transistor based on a cavity-optomechanical system, where the cavity photons interfere with the input signal photons while the pump field controls the transmission spectrum of the signal laser. Theoretical analysis shows such a quantum optomechanical transistor can be switched on or off by turning on or off the pump laser, which corresponds to amplification or attenuation of the signal laser, respectively. The results further demonstrate that the output signal gain is enhanced abruptly with increasing the input pump power. The scheme proposed here will pave the way towards many important applications such as all-optical logic circuits and quantum repeaters. 
Jin-Jin Li, Wei-He and Ka-Di Zhu
quant-ph