Nonreciprocal phonon laser in a rotating cavity optomechanical system with an atomic ensemble

Abstract Phonon lasers, as analogs of optical lasers, have been a topic of considerable interest and research, due to their broad application potential. Here, we theoretically propose a nonreciprocal phonon laser in a hybrid optomechanical system composed of a spin-optomechanical resonator and a two-level atomic ensemble. The results show that the Fizeau drag effect induced by the spin of the resonator leads to significant differences in the mechanical gain, threshold power, and steady-state phonon number when driven from opposite directions, thereby generating a nonreciprocal phonon laser. This offers a new pathway for the experimental realization of nonreciprocal phonon lasers based on the Sagnac effect in spin resonators.