Experimental Quantum Message Authentication with Single Qubit Unitary Operation

We have developed a quantum message authentication protocol that provides authentication and integrity of an original message using single qubit unitary operations. Our protocol mainly consists of two parts: quantum encryption and a correspondence check. The quantum encryption part is implemented using linear combinations of wave plates, and the correspondence check is performed using Hong–Ou–Mandel interference. By analyzing the coincidence counts of the Hong–Ou–Mandel interference, we have successfully proven the proposed protocol experimentally, and also showed its robustness against an existential forgery.