Low jitter up-conversion detectors for telecom wavelength GHz QKD

Abstract

We have developed a hybrid single photon detection scheme for telecom\nwavelengths based on nonlinear sum-frequency generation and silicon\nsingle-photon avalanche diodes (SPADs). The SPAD devices employed have been\ndesigned to have very narrow temporal response, i.e. low jitter, which we can\nexploit for increasing the allowable bit rate for quantum key distribution. The\nwavelength conversion is obtained using periodically poled Lithium niobate\nwaveguides (W/Gs). The inherently high efficiency of these W/Gs allows us to\nuse a continuous wave laser to seed the nonlinear conversion so as to have a\ncontinuous detection scheme. We also present a 1.27GHz qubit repetition rate,\none-way phase encoding, quantum key distribution experiment operating at\ntelecom wavelengths that takes advantage of this detection scheme. The proof of\nprinciple experiment shows a system capable of MHz raw count rates with a QBER\nless than 2% and estimated secure key rates greater than 100 kbit/s over 25 km.\n