Abstract

Several kinds of quantum cryptography schemes have been proposed so far including four-polarization-state cryptography [1], two-nonorthogonal-state cryptography [2], cryptography based on two-photon interferometry [3], cryptography with coherent states [4], and cryptography using time-lag transmission of split photon packets [5], Although the principles for these schemes ate interesting in their own right, the practical feasibility is also important. A cryptography scheme is better if it does not require an arbitrary-polarization-maintaining transmission line, a phase compensator for the transmission line fluctuations, or posttransmission checking of photon-counting timing between Alice and Bob.

© 1996 Optical Society of America