โ Scribed by Naoto Namekata; Yuuki Makino; Shuichiro Inoue
No coin nor oath required. For personal study only.
In order to realize longโdistance quantum cryptography based on standard optical fiber network, we have developed a singleโphoton detector at 1550 nm using InGaAs/InP avalanche photodiodes (APDs). To reduce the dark count probability, APDs were cooled and operated with a Gated Passive Quenching Circuit. A quantum efficiency of 13.7% was obtained at โ55 ยฐC while keeping the dark count probability per gate (2 ns) as low as 2.4 ร 10^โ5^. In this paper we will discuss the performance of the developed singleโphoton detector in view of application to quantum cryptography. ยฉ 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(5): 10โ15, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10115
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## Abstract Quantum key distribution is a new technique that permits secure distribution of a bit string, used as a key in cryptographic protocols. The present quantumโcryptographic protocols use a single photon to carry information; hence, for the construction of an optical setup able to support q