Quantum cryptography with 3-state systems.
We consider quantum cryptographic schemes where the carriers of information are 3-state particles. One protocol uses four mutually unbiased bases and appears to provide better security than obtainable with 2-state carriers. Another possible method allows quantum states to belong to more than one basis. Security is not better, but many curious features arise.
Bechmann-Pasquinucci
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H
Group of Applied Physics, University of Geneva, CH-1211, Geneva 4, Switzerland.
Peres
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A
D003142:Communication; D007257:Information Theory; D011789:Quantum Theory