High-sensitivity force sensing using a phonon laser in an active levitated optomechanical system.

Force detection with high sensitivity is of paramount importance in many fields of study, from gravitational wave detection to investigations of surface forces. Here, we propose and demonstrate a force-sensing method based on gain-enhanced nonlinearity in a nonlinear phonon laser. Experimental and simulation results show that the input force leads to the frequency shift of phonon laser, due to nonlinearity. In addition, we further investigate the influences of the pumping power, numerical aperture, and microsphere's refractive index on the performance of this force-sensing system, regarding the sensitivity and the linear response range. Our work paves a new way towards the realization of precise metrology based on the nonlinearity of phonon laser.

Quantum spinning photonic circulator.

We propose a scheme to realize a four-port quantum optical circulator for critical coupling of a spinning Kerr resonator to two tapered fibers. Its nonreciprocal effect arises from the Fizeau drag induced splitting of the resonance frequencies of the two counter-travelling optical modes. The transmitted photons exhibit direction dependent quantum correlations and nonreciprocal photon blockade occurs for photons transferred between the two fibers. Moreover, the quantum optical circulator is robust against the back scattering induced by intermodal coupling between counter-travelling optical modes. The present quantum optical circulator has significant potential as an elementary cell in chiral quantum information processing without magnetic field.