An Experimental Realization of Quantum Cryptosystem

Toshio HASEGAWA  Tsuyoshi NISHIOKA  Hirokazu ISHIZUKA  Jun'ichi ABE  Katsuhiro SHIMIZU  Mitsuru MATSUI  Shigeki TAKEUCHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E85-A   No.1   pp.149-157
Publication Date: 2002/01/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
quantum cryptography,  key distribution,  error correction,  BB84,  implementation,  

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Quantum cryptography has two advantages in comparison with conventional cryptography: one is that its security is guaranteed by a fundamental physical law, and the other is that it can detect eavesdropping. In this paper, we focus on an experimental realization of quantum cryptography as a total security system. To realize this, we adopt an interferometric optical system using Faraday mirror and improve its optical system. We also utilize semiconductor laser at a short wavelength (830 nm). As a result, we have successfully implemented quantum cryptosystem including error correction and privacy amplification. We confirmed that key distribution was performed at a rate of 1.1 kbps with a 1.7% QBER (quantum bit error rate) over a distance of 200 m (optical fiber). We also show our experimental results over a distance of 1 km (optical fiber) at a rate of 0.76 kbps.