Superdense coding with single-particle entanglement

Recent work has explored the idea that nonlocality or entanglement involving a single particle should be taken seriously and has real measurable consequences. Theoretical and experimental schemes have shown, for example, that single-particle states can violate Bell’s inequalities. Here we discuss the possibility of using single-particle entanglement for implementing a superdense coding protocol. Particle-number superselection rules restrict this scheme to being able to transmit log₂(3) bits of information. While this falls short of the two-particle limit of two bits, it still exceeds what can be achieved without entanglement.