Superdense coding based on intraparticle entanglement states

High channel capacity always plays an important role in quantum communication. Dense coding is an effective way to improve channel capacity, whose core idea is to apply as few particles as possible to carry information. Quantum entanglement exists not only between multiple particles but also in various degrees of freedom of a single-particle (intraparticle entanglement). Compared with the former (entanglement among multi-particles), firstly, the latter (intraparticle entanglement) can enable more bits of information to be transmitted in one-time communication by utilizing more degrees of freedom of single-particle. Secondly, the latter is more robust than the former. Thus, in this paper, based on the current experiment technology level, a scheme is designed to encode, transmit, and process 3 bits of classical information by applying the intraparticle entanglement state of a single-photon with three degrees of freedom in theory. Based on the literature survey, this scheme reaches the level at which a single-photon currently carries the most information with good security and robustness, and this work reveals a good idea for realizing superdense coding.