Quantum Random Number Generation within Idle Time Windows of Quantum Key Distribution

We present a quantum random number generator system that relies on precise time measurements of the intervals between random clicks of single photon detectors. These SPDs are embedded in a quantum key distribution system. During the QKD transfer's time window, the SPDs perform their usual function of measuring the photon state. Outside of this window, the SPDs are subjected to faint laser pulses that induce random clicks on the detectors. A Field Programmable Gate Array is employed to measure the time interval between these random clicks based on an internal 470 MHz clock. The FPGA then transmits a portion of the random measurement to a personal computer. The resulting sequence demonstrates a high degree of randomness, making it a reliable resource for randomness in the QKD process.