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Phys. Rev. Lett. 68, 3121–3124 (1992)

Quantum cryptography using any two nonorthogonal states

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Charles H. Bennett
IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598

Received 23 December 1991; published in the issue dated 25 May 1992

Quantum techniques for key distribution—the classically impossible task of distributing secret information over an insecure channel whose transmissions are subject to inspection by an eavesdropper, between parties who share no secret initially—have been proposed using (a) four nonorthogonally polarized single-photon states or low-intensity light pulses, and (b) polarization-entangled or spacetime-entangled two-photon states. Here we show that in principle any two nonorthogonal quantum states suffice, and describe a practical interferometric realization using low-intensity coherent light pulses.

© 1992 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.68.3121
DOI:
10.1103/PhysRevLett.68.3121
PACS:
03.65.Bz, 42.50.Wm, 89.70.+c