Observation of Ten-photon Entanglement Using Thin BiB${}_3$O${}_6$ Crystals

We report on the experimental realization of a ten-photon Greenberger-Horne-Zeilinger state using thin BiB${}_3$O${}_6$ crystals. The observed fidelity is $0.606\pm 0.029$, demonstrating a genuine entanglement with a standard deviation of 3.6 $\sigma$. This result is further verified using $p$-value calculation, obtaining an upper bound of $3.7\times {10}^{-3}$ under an assumed hypothesis test. Our experiment paves a new way to efficiently engineer BiB${}_3$O${}_6$ crystal-based multi-photon entanglement systems, which provides a promising platform for investigating advanced optical quantum information processing tasks such as boson sampling, quantum error correction and quantum-enhanced measurement.