Differential phase shift quantum key distribution

Phys Rev Lett. 2002 Jul 15;89(3):037902. doi: 10.1103/PhysRevLett.89.037902. Epub 2002 Jun 27.


A novel quantum cryptography scheme is proposed, in which a single photon is prepared in a linear superposition state of three basis kets. A photon split to three pulses is sent from Alice to Bob, where the phase difference between sequential two pulses carries bit information. Bob measures the phase difference by passive differential phase detection. This scheme is suitable for fiber transmission systems and offers a key creation efficiency higher than conventional fiber-based BB84.