Enhancement of photon blockade effect via quantum interference

Nonreciprocal optomechanically induced transparency and enhanced ground-state cooling in a reversed-dissipation cavity system

We explore the prospects of phase-modulated optical nonreciprocity and enhanced ground-state cooling of a mechanical resonator for the reversed-dissipation system, where the dissipative coupling between two cavities is realized through the adiabatic elimination of a low-Q mechanical mode, while a high-Q mechanical mode interacts with two mutually coupled cavities, forming a closed-loop structure. This unique system facilitates the nontrivial phenomenon of optomechanically induced transparency (OMIT), which exhibits asymmetry due to the frequency shift effect. We also observe the emergence of parity-dependent unidirectional OMIT windows (appearing under the phase-matching condition), which can be dynamically modulated by both the phase factors and the strength of the dissipative coupling. Furthermore, our study delves into the ground-state cooling effect operating within the reversed-dissipation regime. Intriguingly, the cooling effect can be significantly enhanced by carefully engineering dissipative complex coupling, such as in the phase-matching condition. The potential applications of this scheme extend to the fabrication of ideal optical isolators in optical communication systems and the manipulation of macroscopic mechanical resonators at the quantum level, presenting exciting opportunities in quantum technologies.

Quantum illumination based on cavity-optomagnonics system with Kerr nonlinearity

Quantum illumination is a quantum optical sensing technique, which employs an entangled source to detect low-reflectivity object immersed in a bright thermal background. Hybrid cavity-optomagnonics system promises to work as quantum illumination because a yttrium iron garnet (YIG) sphere can couple to microwave field and optical field. In this paper, we propose a scheme to enhance the entanglement between the output fields of the microwave and optical cavities by considering the intrinsic Kerr nonlinearity of the YIG. We investigate the difference between intrinsic Kerr nonlinearity and optomagnonical parametric-type coupling on improving entanglement. Our result show that the large value optomagnonical parametric-type coupling does not mean the large entanglement, nevertheless, the large value of Kerr nonlinearity does monotonously improve the entanglement for our group of parameters. Consequently, under feasible parameters of current experiment, the signal-to-noise ratio and probability of detection error can be improved after considering the magnon Kerr nonlinearity.

Conventional photon blockade in the dispersive limit for Tavis-Cummings model

In the dispersive limit, the conventional photon blockade effect cannot be realized due to the absence of photon nonlinearity. We propose a scheme to recover the photon blockade effect of the dispersive Tavis-Cummings model, which makes it possible to realize the conventional photon blockade effect in the dispersive limit. It is shown that both single-photon and two-photon blockade effects can be recovered at appropriate qubit driving strength. The optimal qubit drive strength and cavity field drive detuning are given analytically. All analyses can be verified by numerical simulation, and the strongest photon blockade effect with the largest average photon number can be produced when the single excitation resonance condition is satisfied. Moreover, we find that the achieved two-photon blockade effect is relatively robust to thermal noise. Our proposal is able to obtain single-photon sources with high purity and high brightness and has great potential for applications in quantum communication processing.

Enantiodiscrimination of chiral molecules via quantum correlation function

We propose a method to realize enantiodiscrimination of chiral molecules based on quantum correlation function in a driven cavity-molecule system, where the chiral molecule is coupled with a quantized cavity field and two classical light fields to form a cyclic three-level model. According to the inherent properties of electric-dipole transition moments of chiral molecules, there is a π-phase difference in the overall phase of the cyclic three-level model for the left- and right-handed chiral molecules. Thus, the correlation function depends on this overall phase and is chirality-dependent. The analytical and numerical results indicate that the left- and right-handed chiral molecules can be discriminated by detecting quantum correlation function. Our work opens up a promising route to discriminate molecular chirality, which is an extremely important task in pharmacology and biochemistry.

Improving few-photon optomechanical effects with coherent feedback

Few-photon effects such as photon blockade and tunneling have potential applications in modern quantum technology. To enhance the few-photon effects in an optomechanical system, we introduce a coherent feedback loop to cavity mode theoretically. By studying the second-order correlation function, we show that the photon blockade effect can be improved with feedback. Under appropriate parameters, the photon blockade effect exists even when cavity decay rate is larger than the single-photon optomechanical coupling coefficient, which may reduce the difficulty of realizing single-photon source in experiments. Through further study of the third-order correlation function, we show that the tunneling effect can also be enhanced by feedback. In addition, we discuss the application of feedback on Schrödinger-cat state generation in an optomechanical system. The result shows that the fidelity of cat state generation can be improved in the presence of feedback loop.

Nonreciprocal conventional photon blockade in driven dissipative atom-cavity

In this Letter, we propose a scheme to achieve a nonreciprocal conventional photon blockade in a nonlinear device consisting of an atom and spinning cavity by manipulating the detuning between the atom and the cavity. We show that the single-photon blockade can be generated by driving the spinning resonator from one side, while photon-induced tunneling is driven by the other side with the same driving strength. This nonreciprocal conventional photon blockade effect originates from the Fizeau-Sagnac drag, which leads to different splitting of the resonance frequencies for the counter-circulating modes. We give four optimal solutions for Fizeau-Sagnac shifts to generate a nonreciprocal conventional photon blockade with the arbitrary detunings between atom and cavity.