High-dimensional Bell-state preparation and characterization based on single-photon radial and azimuthal mode multiplexing
Feng-Pei Li, Feng-Pei Li, Shiyue Jia +4 more
Laguerre–Gaussian (LG) modes are characterized by two integer parameters, p and l , which correspond to the radial and azimuthal modes of photons. Both degrees of freedom are discrete and high-dimensional, and each can be used to construct a high-dimensional Hilbert space. Here, we use the radial-azimuthal modes of a single photon to construct two-dimensional and four-dimensional Bell states and experimentally realize full single-photon Bell-state characterization, thereby verifying the orthogonality and completeness of the Bell states. Subsequently, we measure the magnitude and phase of a four-dimensional superposition state in a 16-dimensional Hilbert space, obtaining results in good agreement with theoretical predictions, which further confirms the completeness of the four-dimensional Bell basis. Our experiment demonstrates that the radial and azimuthal modes of a single photon play equally important roles. Multiplexing these two degrees of freedom enables the construction of higher-dimensional Hilbert spaces and significantly enhances the information-carrying capacity of a single photon. Our results hold potential applications in the development of quantum communication protocols with high channel capacity.
Photonics Research•Jun 22, 2026•0 citations