Afterpulse-like phenomenon of superconducting single photon detector in high speed quantum key distribution system
Mikio Fujiwara, Akihiro Tanaka, Satoshi Takahashi, K. Yoshino, Yasusada Nambu, A. Tajima, Shigehito Miki, Taro Yamashita, Zhixin Wang, Akihisa Tomita, Masahide Sasaki · Optics Express · 2011
We discuss our estimates of the performance of a superconducting single photon detector (SSPD) in a high speed quantum key distribution (QKD) system. We find that at high repetition operation reflections from the readout circuit at room temperature causes an afterpulse-like phenomenon, and drastically increases the quantum bit error rate (QBER). Such effects are not seen during low frequency operation. By using an amplifier with a small reflection coefficient S11, we succeed in reducing the afterpulse-like phenomenon and increasing a secure key rate.