QUANTUM CRYPTOGRAPHY BASED ON SPLIT TRANSMISSION OF ONE-BIT INFORMATION IN 2 STEPS

We propose a simple quantum cryptographic scheme involving truly two o rthogonal states. The security of the protocol is based on splitting t he transfer of one-bit information into two steps, ensuring that only a fraction of the bit information is transmitted at a time. A particul ar implementation with an asymmetric interferometer is presented, whic h does not require the random timing of the packet sending as was used by Goldenberg and Vaidman [Phys. Rev. Lett. 75, 1239 (1995)].