Coexistence of High-Bit-Rate Quantum Key Distribution and Data on Optical Fiber

Quantum key distribution (QKD) uniquely allows the distribution of cryptographic keys with security verified by quantum mechanical limits. Both protocol execution and subsequent applications require the assistance of classical data communication channels. While using separate fibers is one option, it is economically more viable if data and quantum signals are simultaneously transmitted through a single fiber. However, noise-photon contamination arising from the intense data signal has severely restricted both the QKD distances and secure key rates. Here, we exploit a novel temporal-filtering effect for noisephoton rejection. This allows high-bit-rate QKD over fibers up to 90 km in length and populated with error-free bidirectional Gb=s data communications. With a high-bit rate and range sufficient for important information infrastructures, such as smart cities and 10-Gbit Ethernet, QKD is a significant step closer toward wide-scale deployment in fiber networks.
K. A. Patel,1,2 J. F. Dynes,1 I. Choi,1 A.W. Sharpe,1 A. R. Dixon,1 Z. L. Yuan,1,* R.V. Penty,2 and A. J. Shields1,
1Toshiba Research Europe Limited, Cambridge Research Laboratory, 208 Cambridge Science Park, Milton Road, Cambridge, CB4 0GZ, United Kingdom
2Cambridge University Engineering Department, 9 J J Thomson Avenue, Cambridge, CB3 0FA, United Kingdom

(Received 22 June 2012; published 20 November 2012)
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