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.
The photonic Spin Hall Effect (SHE) causes a polarization dependent transverse shift of light at an interface. In this paper, we theoretically investigate the microwave controlled photonic SHE and microwave electrometry in a closed-loop
Λ-type atomic system. At zero probe detuning (
Δp=0) and relative phase
φ=0,π, the photonic SHE magnitude remains at the intrinsic finite beam saturation limit
w0/2, whereas the microwave field shifts its angular position linearly with opposite slopes (signs) for the two phases, enabling differential microwave electric field sensing. At
φ=π/2, the photonic SHE magnitude decays exponentially with
Ωμ, providing weak microwave electric field sensing. In contrast, at
Δp=±Ωc (control field coupling), the photonic SHE reaches a maximum of half the incident beam waist when
Ωμ≥Ωp and the phase
φ is optimized. Interestingly, we observed microwave controlled switching of photonic SHE by tuning the relative phase
φ at an optimized value of
Ωμ and
Ωc. Our results may have potential applications in microwave quantum sensing and quantum optical switches based on the photonic SHE.
Abstract The Photonic spin Hall effect (PSHE) offers fundamental insights into spin–orbit interactions of light, yet its control over compact, tunable platforms remains a challenge. Here, we investigate the PSHE in a solid-state platform of N -coupled quantum dots (CQDs), focusing on both the linear absorption and Kerr nonlinear regimes. On this platform, an external electric field controls electron tunneling between CQDs, resulting in multiple tunneling-induced transparency windows. We report a giant enhancement of the Kerr nonlinearity, achieving orders-of-magnitude increases while suppressing linear absorption—a domain that is favorable for low-power nonlinear photonics. Exploiting this, we demonstrate that the PSHE shift can be drastically enhanced and controlled by tuning the excited-state transition frequency and tunneling strengths, which significantly modify the Brewster angle. This active nonlinear control improves static nanostructures by combining the tunability of atomic systems with the functionality of an integrable quantum material. Our results establish N -CQDs as a viable platform for producing giant Kerr nonlinearity-driven PSHE, opening up new possibilities for tunable low-power spin–orbit light control in quantum photonics.