Abstract The magnon blockade effect in a parity‐time () symmetric‐like three‐mode cavity magnomechanical system involving the magnon–photon and magnon–phonon interactions is investigated. In the broken and unbroken ‐symmetric regions, the second‐order correlation function is calculated analytically and numerically, respectively, and the optimal value of detuning is further determined. By adjusting different system parameters, the different blockade mechanisms are studied and it is found that the perfect magnon blockade effect can be observed under the weak parameter mechanism. This work paves a way to achieve the magnon blockade in experiment.
Abstract The magnon blockade effect in a parity‐time () symmetric‐like three‐mode cavity magnomechanical system involving the magnon–photon and magnon–phonon interactions is investigated. In the broken and unbroken ‐symmetric regions, the second‐order correlation function is calculated analytically and numerically, respectively, and the optimal value of detuning is further determined. By adjusting different system parameters, the different blockade mechanisms are studied and it is found that the perfect magnon blockade effect can be observed under the weak parameter mechanism. This work paves a way to achieve the magnon blockade in experiment.
Abstract A scheme that harnesses magnon squeezing under weak pump driving within a cavity magnomechanical system to achieve a robust magnon (photon) blockade is proposed. Through meticulous analytical calculations of optimal parametric gain and detuning values, the objective is to enhance the second‐order correlation function. The findings demonstrate a substantial magnon blockade effect under ideal conditions, accompanied by a simultaneous photon blockade effect. Impressively, both numerical and analytical results are found to be in complete accord, providing robust validation for the consistency of the findings. It is anticipated that the proposed scheme will serve as a pioneering approach toward the practical realization of magnon (photon) blockade in experimental cavity magnomechanical systems.
ABSTRACT We focus on the magnon blockade phenomenon in a non‐Hermitian cavity magnonics system with dissipative magnon–photon coupling. The system consists of a cross‐shaped microwave circuit supporting both standing and traveling waves and a yttrium iron garnet sphere supporting a magnon mode, where the dissipative coupling between the magnon mode and the standing wave cavity mode is caused by the traveling wave, forming the non‐Hermitian cavity magnonics system. For the non‐Hermitian system with the pure dissipative coupling, we find that, by driving the microwave cavity mode using the two‐photon driving field, the magnon blockade phenomenon can occur due to the destructive interference of the transition paths. More excitingly, when the non‐Hermitian cavity magnonics system is set as an anti‐parity‐time ()‐symmetry system, the optimal magnon blockade phenomenon occurs near the exceptional points (transition points from the unbroken‐ to broken‐anti‐ symmetry). Then we analyze the influence of the driving strength on the magnon blockade, and give the optimal driving strength. The presented work not only provides an alternative method for the magnon blockade, but also can promote the study of the quantum effects in the non‐Hermitian cavity magnonics system.
We study the effects of parity-time (PT) symmetry on the photon blockade and distinguish the different blockade mechanisms in a double-cavity optomechanical system. By studying the light statistics of the system, we find the completely different photon blockade behaviors when the PT symmetry is broken or unbroken, which is related to the PT phase transition. Furthermore, an interesting phenomenon that the two cavities are blocked at the same time is found with the appropriate system parameters. Those statistical phenomena are all analyzed in detail and demonstrated by analytically solving the Schr\"odinger equation and numerically simulating the master equation, respectively. Finally, we also consider the non-PT-symmetric situations which further reveal the physical essence of the photon blockade by comparing those results. Different from the usual photon blockade, our proposal is feasible even with weak parameter mechanism, i.e., the proposal neither requires the strong optomechanical coupling nor the large tunneling coupling between cavities.
Photonic spin Hall effect in PT-symmetric non-Hermitian cavity magnomechanics
Non-Hermitian cavity magnomechanics (CMM), which incorporates the magnon-photon and magnon-phonon interactions simultaneously, enables rich physical phenomena, including exceptional-point-enhanced sensing, and offers pathways toward topological transitions and nonreciprocal quantum transformation. These interactions exert a pivotal influence on the optical response of a weak probe field and pave the way for novel applications in quantum technologies. In this work, we consider a yttrium-iron-garnet (YIG) sphere coupled to a microwave cavity. The magnon mode of the YIG sphere is directly excited through microwave field coupling, whereas the cavity mode is probed via a weak-field interrogation scheme. The direct interaction of a traveling field with the magnon mode induces gain in the system, thereby establishing non-Hermitian dynamics. The parity-time (PT)-symmetric behavior of a hybrid non-Hermitian CMM is designed and investigated. Eigenvalue spectrum analysis demonstrates that a third-order exceptional point (EP_3) emerges under tunable effective magnon-photon coupling when the traveling field is oriented at an angle of π/2 relative to the cavity's x-axis. The photonic spin Hall effect (PSHE) in a reflected probe field is subsequently examined in such a system. Under balanced gain and loss conditions and in the presence of effective magnon-phonon coupling, tunable effective magnon-photon coupling enables coherent control of the PSHE across the broken PT-symmetric phase, at the EP_3, and in the PT-symmetric phase. Investigation reveals that the PSHE can be significantly enhanced or suppressed via effective magnon-photon coupling. The influence of intracavity length on the PSHE is further explored, providing an additional parameter for fine-tuning the transverse shift. These findings establish a direct correspondence between the PSHE and the underlying non-Hermitian eigenvalue spectrum.
Abstract Unconventional magnon and photon blockade have attracted significant research interest for their ability to generate single‐particle sources in hybrid quantum systems, particularly in cavity magnonics. In this work, a scheme is presented to investigate the effect of Barnett effects in the nonreciprocal blocked of magnons and photons within a spinning microwave magnomechanical system with a squeezed input drive of the magnonic mode. The effects of thermal noise, the amplitude of a probe field, and the magnetic‐dipole coupling strength are realized using the weak‐coupling regime. Using the Mandel parameter, the nonclassicality of the system is discussed. Additionally, the time evolution of the second‐order correlation function is examined.
A hybrid system established by the direct interaction between a magnon mode and a superconducting transmon qubit is used to realize a high-degree blockade for magnon. It is a fundamental way toward quantum manipulation at the level of a single magnon and preparation of single magnon sources. Through weakly driving the magnon and probing the qubit, our magnon-blockade proposal can be optimized when the transversal coupling strength between the magnon and qubit is equivalent to the detuning of the qubit and the probing field or that of the magnon and the driving field. Under this condition, the equal-time second-order correlation function g(2)(0) can be analytically minimized when the probing intensity is about three times the driving intensity. Moreover, the magnon blockade could be further enhanced by proper driving intensity and system decay rate, whose magnitudes outrange the current systems of cavity QED and cavity optomechanics. In particular, the correlation function achieves ${g}^{(2)}(0)\ensuremath{\sim}{10}^{\ensuremath{-}7}$, about two orders lower than that for the photon blockade in cavity optomechanics. Also, we discuss the effects on g(2)(0) from thermal noise and the extra longitudinal interaction between the magnon and qubit. Our optimized conditions for blockade are found to persist in these nonideal situations.