An Experimental Realization of Quantum Cryptosystem

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

Publication
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: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
quantum cryptography,  key distribution,  error correction,  BB84,  implementation,  

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Summary: 
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.