A linear optical unambiguous discrimination of hyperentangled Bell states is proposed for two-photon systems entangled in both the polarization and momentum degrees of freedom (DOFs) assisted by time bin. This unambiguous discrimination scheme can completely identify 16 orthogonal hyperentangled Bell states using only linear optical elements, where the function of the auxiliary entangled Bell state is replaced by time bin. Moreover, the possibility of extending this scheme for distinguishing hyperentangled Bell states in n DOFs is discussed, and it shows that 2 n+k+1 hyperentangled Bell states in n (n ≥ 2) DOFs can be distinguished with k (k < n) auxiliary entangled states of additional DOFs by introducing a time delay, which decreases the auxiliary entanglement resource required for unambiguous discrimination of hyperentangled Bell state. Therefore, this scheme provides a new way for distinguishing hyperentangled states with current technology, which will extend the application of discrimination of hyperentangled states via linear optics to other quantum information protocols besides hyperdense coding schemes in the future. IntroductionPhoton system is one of the most interesting candidates for quantum communication with the character of manipulability, high-speed transmission, and high capacity. The entangled photon system is a crucial quantum resource in quantum communication, which has many important applications in quantum communication protocols, such as quantum key distribution, [1][2][3][4] quantum secret sharing, [5] quantum dense coding, [6,7] quantumThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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