Three-party quantum secret sharing based on freqeuncy-bin entangled biphotons

Quantum secret sharing (QSS) offers intrinsic information-theoretic security via the no-cloning theorem and measurement-induced disturbance, enabling built-in eavesdropping detection beyond classical schemes that rely on computational assumptions. Among physical platforms, photons are ideal carriers for long-distance quantum information distribution over existing telecom networks. Also, frequency encoding scheme provides fiber robustness, dense multiplexing capability, and compatibility with chip-integrable components. In this work, we experimentally demonstrate a three-party QSS protocol using positively correlated frequency-bin biphoton Bell states generated through dual-line pumping of a spontaneous parametric down-conversion (SPDC) crystal. The source itself acts as one participant, while the signal and idler photons are delivered to the other two parties through optical fiber and wavelength-division multiplexing (WDM) routing in a nonlocal geometry. The protocol is implemented by combining state choices at the source with measurement-basis choices at the remote parties. In our setup, fast switching is supported in both state preparation and measurement stages, and we observe near-ideal three-party correlations required for QSS. These results establish a viable photonic approach toward practical QSS among distant nodes.