Abstract We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon–photon interaction via the backward stimulated Brillouin scattering (BSBS) process. The coherent photon–phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator. The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly. When the Duffing nonlinearity is weak, the squeezing degree of the mechanical mode in the presence of BSBS can be improved by more than one order of magnitude compared with that in the absence of BSBS. Our scheme may be extended to other quantum systems to study novel quantum effects.
We propose a scheme to generate large amount of mechanical squeezing, far beyond the
3dB limit, which is based on synthetic magnetism in optomechanical system that hosts a Backward Stimulated Brillouin Scattering (BSBS) process. Our benchmark system consists of an acoustic mode coupled to two optical modes through the BSBS process, and a Duffing mechanical oscillator that couples to the same optical modes through the standard optomechanical radiation pressure. The synthetic magnetism comes from the modulation of the mechanical coupling between the acoustic and the mechanical mode. When there is no synthetic magnetism, a given amount of mechanical squeezing is generated in the system. This squeezing is mainly dependent on the BSBS process, and it is fragile against thermal noise. By switching on the synthetic magnetism, the degree of the generated squeezing is greatly enhanced and goes far beyond the limit of the
3dB. This large magnetism induced squeezing persists even when there is no BSBS process in the system. Moreover, this generated squeezing is robust enough against thermal noise in comparison to the one induced when the synthetic magnetism is off. Furthermore, both the mechanical variance squeezing and effective phonon number exhibit series of peaks and dips depending on the phase modulation of the mechanical coupling. This oscillatory feature is reminiscent of a sudden death and revival of squeezing phenomenon, which can be used to maintain a desired magnitude of squeezing by tuning this phase. Our proposal provides a path toward a flexible scheme that generates large amount of squeezing, far beyond the
3dB limit. Such a generated squeezed states can be used for quantum applications including quantum information processing, quantum sensing and metrology, and quantum computing.
Abstract The simultaneous ground-state cooling and the quantum synchronization of multiple mechanical oscillators are very important in the study of the quantum coherence of the optomechanical system with multiple mechanical modes. In this paper, we propose a scheme for investigating the simultaneous ground-state cooling and the quantum synchronization of two mechanical oscillators based on an optomechanical system via backward stimulated Brillouin scattering. A photon-phonon interaction via the backward stimulated Brillouin scattering process is introduced in this scheme, which is beneficial for cooling the optomechanical system. It is found that simultaneous ground-state cooling and quantum synchronization of two mechanical oscillators can be achieved when a suitable photon-phonon coupling via the backward stimulated Brillouin scattering process is chosen. Quantum synchronization is enhanced with the help of the photon-phonon coupling via the backward stimulated Brillouin scattering process. In addition, the relation between simultaneous ground-state cooling and quantum synchronization is discussed. It turns out that the appearance of simultaneous ground-state cooling is accompanied by quantum synchronization, but simultaneous ground-state cooling may not be realized when quantum synchronization is achieved. Our scheme paves a new way for the control of the quantum properties of the mechanical oscillators based on optomechanical system.