Effect of Attenuation and Dispersion in the Communication Channel on the   Secrecy of a Quantum Cryptosystem
  The effects of dispersion in the communication channel on the secrecy of a quantum cryptosystem based on single photon states with different frequencies are studied. A maximum communication channel length which can still ensure the secrecy of the key generation procedure is found. 
S.N.Molotkov (Institute of Solid State Physics of the Russian Academy   of Sciences)