Tunable photonic spin Hall effect in a tripod atom-light configuration

We propose a four-level tripod atom-light coupling scheme to manipulate the photonic spin Hall effect (PSHE) in the reflected probe light. Our study demonstrates that the tripod configuration enables enhanced PSHE near the Brewster angle upon reflection for the probe field, with significantly stronger transverse shifts at resonance compared to off-resonance conditions. The PSHE shift is maximized when all fields are resonant, aligning with the transparency point of the system, and is notably weaker under off-resonant conditions, where gain effects dominate. Additionally, the tripod scheme enables an enhanced transverse shift for the signal field at resonance, resulting in dual-field PSHE enhancement. This combined enhancement of transverse shift for both probe and signal fields underscores the superiority of the tripod configuration in achieving maximized PSHE shifts, surpassing prior schemes and opening new possibilities for advanced applications in spin-photonic devices.