One-step quantum dialogue

Quantum dialogue (QD) enables two communication parties to directly exchange secret messages simultaneously. In conventional QD protocols, photons need to transmit in the quantum channel for two rounds. In this paper, we propose a one-step QD protocol based on the hyperentanglement. With the help of the non-local hyperentanglement-assisted Bell state measurement (BSM), the photons only need to transmit in the quantum channel once. We prove that our one-step QD protocol is secure in theory and numerically simulate its secret message capacity under practical experimental condition. Comparing with previous QD protocols, the one-step QD protocol can effectively simplify the experiment operations and reduce the message loss caused by the photon transmission loss. Meanwhile, the non-local hyperentanglement-assisted BSM has a success probability of 100% and is feasible with linear optical elements. Moreover, combing with the hyperentanglement heralded amplification and purification, our protocol is possible to realize long-distance one-step QD.