Wang, YD (reprint author), Chinese Acad Sci, Inst Theoret Phys, State Key Lab Theoret Phys, Beijing 100190, Peoples R China.
In this work, we study an entanglement concentration scheme in a 3-mode optomechanical system. The scheme is based on phonon counting measurements, which can be performed through photon counting of an auxiliary cavity connected to the mechanical resonator. The amount of entanglement between the two cavity output modes is found to increase logarithmically with the number of detected phonons ( photons). Such an entanglement concentration scheme is deterministic since, independently of the number of detected phonons ( photons), the measurement always leads to an increase in output entanglement. Besides numerical simulations, we provide analytical results and physical insight for the improved entanglement and the concentration efficiency.