Secure communication using mesoscopic coherent states

Abstract

We demonstrate theoretically and experimentally that secure communication using intermediate-energy (mesoscopic) coherent states is possible. Our scheme is different from previous quantum cryptographic schemes in that a short secret key is explicitly used and in which quantum noise hides both the bit and the key. This encryption scheme can be optically amplified. New avenues are open to secure communications at high speeds in fiber-optic or free-space channels.

Text accepted to PRL in 04/21/03. Minor text improvements over former quant-ph version