Jun Zou

An integrated chip system for MDI-QKD is demonstrated. The MDI-QKD transmitter chips and server chip work on a key rate per pulse of 2.923 × 10^(-6) over a distance corresponding to 50-km optical fiber with 25% detection efficiency.

In this study, a high integrated and broadband entropy source of quantum random number generator (QRNG) based on the vacuum fluctuation is designed and verified experimentally. The size of hybrid chip, which is the heart core of entropy source, composed of laser chip and silicon photonics chip is reduced to 6.3×2.6×1.5 mm3. The 3 dB bandwidth of the balanced homodyne detector in entropy source based on cascaded radio frequency amplifier is 2.4 GHz, and the common mode rejection ratio was greater than 25 dB. A quantum to classical noise ratio of 9.48 dB was achieved when the photoelectron current is 1 mA. The noise equivalent power is 8.85 pW/√Hz, and the equivalent transimpedance is 22.8 K. The equalizer technology is utilized to optimize the quantum random number generation rate by eliminate the dependence of the adjacent samples. The quantum random number generation speed can achieve 67.9 Gbps under average conditional minimum entropy and 61.9 Gbps under worst-case conditional minimum entropy. The hybrid chip in our paper promote the QRNG entropy source based on vacuum fluctuation to a higher integration and faster stage.