GHz QKD at telecom wavelengths using up-conversion detectors

摘要

We have developed a hybrid single photon detection scheme for telecomwavelengths based on nonlinear sum-frequency generation and siliconsingle-photon avalanche diodes (SPADs). The SPAD devices employed have beendesigned to have very narrow temporal response, i.e. low jitter, which we canexploit for increasing the allowable bit rate for quantum key distribution. Thewavelength conversion is obtained using periodically poled Lithium niobatewaveguides (W/Gs). The inherently high efficiency of these W/Gs allows us touse a continuous wave laser to seed the nonlinear conversion so as to have acontinuous detection scheme. We also present a 1.27GHz qubit repetition rate,one-way phase encoding, quantum key distribution experiment operating attelecom wavelengths that takes advantage of this detection scheme. The proof ofprinciple experiment shows a system capable of MHz raw count rates with a QBERless than 2% and estimated secure key rates greater than 100 kbit/s over 25 km.