2026/07/30 by Yan Zhang, Xiang Liu, Hou Ian
Physics and Astronomy · #quant-ph #physics.optics
arxiv created 2026/07/30 · arxiv updated 2026/07/31
The four laws by Arago and Fresnel distinguish the coplanarity of two light beams to determine their capacity of interference, laying the historic milestone for conceptualizing the polarization of light. Equipped with modern descriptions of non-classical states, we re-investigate the macroscopic Arago-Fresnel interference producible by photon helicities. To this end, we compute the Stokes parameter of a polarized beam combined from a regular coherent state (displaced from the vacuum) and a displaced single-photon spin state (displaced from either a left- or right-spin state of photon). The spin orientation, together with its relative asymmetry with respect to the polarizing orientation of the displacing coherent state, produces distinguishing parameter dependences and thus distict interference fringes. Conversely, this quantum interferometry establishes a purely optical method to determine the spin of an unknown incident photon.