Spin Bunching Of Conjugated Structured Photons Based On Metasurfaces

ABSTRACT The multi‐photon bunching effect, arising from intrinsic bosonic exchange symmetry in path interference, underpins numerous quantum information techniques. However, conventional bunching in real space faces challenges in tailoring complex structured light fields. Here, we leverage dielectric metasurfaces with polarization entanglement to generate conjugated structured photons and achieve active control over nonlocal spin bunching between two photons. In the prepared spin–orbit hybrid entangled state, projective spin measurement on the idler photon nonlocally heralds the creation of a conjugated structured photon in the signal arm, residing on a higher‐order Poincaré sphere. By adjusting the relative phase to alter entanglement properties, continuous control can be achieved from spin bunching to anti‐bunching. Exploiting this phase sensitivity enables reconstruction of the conjugated photon's complex amplitude. This work establishes spin bunching as a paradigm for quantum correlation control and demonstrates metasurfaces as a compact, multifunctional platform for structured photonic quantum state engineering and metrology.