Experimental Demonstration of a Macroscopic Cryptography Technique

Physical layer cryptography offers the unique possibility of certifiably secure data transmission between remote locations. We present here for the first time, to our knowledge, the experimental results of a secure full Poincare occupancy polarization encrypted data transmission system. The scheme uses an approach to macroscopic physical layer cryptography based on combining a multilevel polarisation modulation cipher with a differential phase shift keying data transmission technique. Depolarized noise is added to the encrypted data so as to hide both the data and key from a potential eavesdropper. Experimental results prove the effectiveness of the technique over amplified optical transmission links. The technique hence opens up new avenues for long distance secure data transmission over fibre links