Quantum cryptography using larger alphabets - art. no. 062308

Like all of quantum information theory, quantum cryptography is traditional ly based on two-level quantum systems. In this paper, a protocol for quantu m key distribution based on higher-dimensional systems is pre sented. An ex perimental realization using an interferometric setup is also proposed. Ana lyzing this protocol from the practical side, one finds an increased key cr eation rate while keeping the initial laser pulse rate constant. Analyzing it for the case of intercept/resend eavesdropping strategy, an increased er ror rare is found compared to two-dimensional systems, hence an advantage f or the legitimate users to detect an eavesdropper.