Magnon blockade is an effective physical mechanism to generate a single magnon, which is of great importance in quantum information processing. We present a scheme to realize the unconventional magnon blockade effect by using Kerr nonlinearity in a cavity electromagnonic system. Under weak driving conditions, we give the optimal parameter conditions for magnon antibunching through analytical calculations, which are in good agreement with numerical results. Furthermore, we find that Kerr nonlinearity is necessary to create magnon blockade. In particular, unconventional magnon blockade can be achieved in both weak nonlinearity and weak coupling regimes. The present scheme indicates a method for generating unconventional magnon blockade effect and provides a feasible and flexible platform for the realization of a single-magnon source with high purity.

We propose a scheme to enhance photon blockades simultaneously in two microwave cavities connected by a giant atom. In the case that only one cavity is weakly driven, we observe that the enhanced photon blockades occur in both cavities at the same time, which is attributed to the anharmonic eigenenergy spectrum constructed by the resonantly coupled giant atom. When the cavity and the atom are simultaneously driven, the stronger photon blockades in two cavities can be successfully achieved by the destructive quantum interference of two-photon excitation. Interestingly, we find that high single-photon occupations can be obtained in both cases. Moreover, we give the optimal conditions for conventional and unconventional photon blockades through analytical calculations, which are in good agreement with numerical results. Our scheme opens a prospective path to achieve simultaneous photon blockades in two indirectly coupled cavities, and provides a promising method to generate the high-quality and brightness single photon source.

We theoretically propose a scheme for generating nonreciprocal macroscopic bipartite and tripartite entanglement using the Barnett effect in cavity-magnon optomechanics. The system consists of an optomechanical cavity and a rotatable yttrium iron garnet (YIG) sphere. Our results indicate that under appropriate parameter conditions, both bipartite entanglement and genuine tripartite entanglement can be generated between the cavity mode, mechanical mode, and magnon mode. Moreover, when the YIG sphere rotates, adjusting the magnetic field direction can induce a positive or negative Barnett shift, which leads to the nonreciprocity of entanglement, where entanglement exists in one chosen magnetic field direction and disappears in the other. Meanwhile, the macroscopic tripartite entanglement in the system is robust against thermal noise. Our work provides a possible avenue for quantum information processing, quantum chiral device integration, and multi-node quantum networks construction.

We propose a scheme to achieve a tunable nonreciprocal magnon laser with parametric amplification in a hybrid cavity optomagnonical system, which consists a yttrium iron garnet (YIG) sphere and a spinning resonator. We demonstrate the control of magnon laser can be enhanced via parametric amplification, which make easier and more convenient to control the magnon laser. Moreover, we analyze and evaluate the effects of pump light input direction and amplification amplitude on the magnon gain and laser threshold power. The results indicate that we can obtian a higher magnon gain and a broader range of threshold power of the magnon laser. In our scheme both the nonreciprocity and magnon gain of the magnon laser can be increased significantly. Our proposal provides a way to obtain a novel nonreciprocal magnon laser and offers new possibilities for both nonreciprocal optics and spin-electronics applications.

We propose a scheme to achieve nonreciprocal parity-time (PT)-symmetric magnon laser in a PT-symmetric cavity optomagnonical system. The system consists of active and passive optical spinning resonators. We demonstrate that the Fizeau light-dragging effect induced by the spinning of a resonator results in significant variations in magnon gain and stimulated emitted magnon numbers for different driving directions. We find that utilizing the Fizeau light-dragging effect allows the system to operate at ultra-low thresholds even without reaching gain-loss balance. A one-way magnon laser can also be realized across a range of parameters. High tunability of the magnon laser is achieved by changing the spinning speed of the resonators and driving direction. Our work provides a new way to explore various nonreciprocal effects in non-Hermitian magnonic systems, which may be applied to manipulate photons and magnons in multi-body non-Hermitian coupled systems.

We propose a method for realizing the nonreciprocal unconventional photon blockade (NUPB) effect in a spinning microwave magnomechanical system. We determine the optimal parameter conditions for achieving this effect and observe that the numerical solutions are in excellent agreement with the analytical results. Under these optimal conditions, driving the system from the right induces photon antibunching, while driving from the left with identical amplitude leads to photon bunching. This pronounced asymmetry gives rise to NUPB, which arises from the combined effects of destructive quantum interference in two-photon excitation pathways and the Sagnac effect. Furthermore, NUPB can be tuned by adjusting the angular velocity of the microwave resonator. This work provides significant theoretical support for the realization of nonreciprocal single-photon sources and opens new avenues for the design and application of nonreciprocal quantum devices.