We study theoretically the features of the output field of a quadratically coupled optomechanical system assisted with three-level atoms. In this system, the atoms interact with the cavity field and are driven by a classical field, and the cavity is driven by a strong coupling field and a weak signal field. We find that there exists a multi-window transparency phenomenon. The width of the transparent windows can be adjusted by controlling the system parameters, including the number of the atoms, the powers of the lasers driving the atoms and driving the cavity, and the environment temperature. We also find that a tunable switch from fast light to slow light can be realized in this system.
In this paper, the entanglement dynamics of two two-level atoms trapped in coupled cavities with a Kerr medium is investigated, We find that the phenomena of entanglement sudden death （ESD） and entanglement sudden birth （ESB） appear during the evolution process. The influences of initial atomic states, Kerr medium, and cavity-cavity hopping rate on the atom-atom entanglement are discussed. The results obtained by the numerical method show that the atom- atom entanglement is strengthened and even prevented from ESD with increasing cavity-cavity hopping rate and Kerr nonlinearity.
We propose a system for achieving some adjustable quantum coherence effects, including the normal-mode splitting（NMS）, the optomechanically induced transparency（OMIT）, and the optomechanically induced absorption（OMIA）. In this system, two tunnel-coupled optomechanical cavities are each driven by a coupling field and coupled to an atomic ensemble.Besides, one of the cavities is also injected with a probe field. When the system works under different conditions, we can obtain the NMS, the OMIT, and the OMIA, respectively. These effects can be flexibly adjusted by the tunnel coupling between the two cavities, the power of the coupling lasers, and the coupling strength between the atomic ensembles and the cavity fields. Furthermore, we can realize the OMIT even if the oscillating mirrors have relatively larger decay rates.
We investigate the phase sensitivity of the SU（1,1） interfereometer [SU（1,1）I] and the modified Mach-Zehnder in- terferometer （MMZI） with the entangled coherent states （ECS） as inputs. We consider the ideal case and the situations in which the photon losses are taken into account. We find that, under ideal conditions, the phase sensitivity of both the MMZI and the SU（1,1）I can beat the shot-noise limit （SNL） and approach the Heisenberg limit （HL）. In the presence of photon losses, the ECS can beat the coherent and squeezed states as inputs in the SU（1,1）I, and the MMZI is more robust against internal photon losses than the SU（1,1）I.
We investigate the effects of the Casimir force on the output properties of a hybrid optomechanical system. In this system, a nanosphere is fixed on the movable-mirror side of the standard optomechanical system, and the nanosphere interacts with the movable-mirror via the Casimir force, which depends on the mirror–sphere separation. In the presence of the probe and control fields, we analyze the transmission coefficient and the group delay of the field-component with the frequency of the probe field. We also study the transmission intensity of the field-component with the frequency of a newly generated four-wave mixing(FWM) field. By manipulating the Casimir force, we find that a tunable slow light can be realized for the field-component with the frequency of the probe field, and the intensity spectrum of the FWM field can be enhanced and shifted effectively.
We theoretically study the optical nonreciprocity in a piezo-optomechanical microdisk resonator,in which the cavity modes and the mechanical mode are optically pumped and piezoelectrically driven,respectively.For asymmetric optical pumping and different piezoelectrical drivings,our system shows some nonreciprocal optical responses.We find that our system can function as an optical isolator,a nonreciprocal amplifier,or a nonreciprocal phase shifter.
