Abstract: A quantum random number generator (QRNG) is one which extracts genuine randomness from the inherent uncertainty in quantum mechanics based on a quantum system. Previous QRNGs have been implemented with the most common relying on the behavior of a photon at a beamsplitter, producing a random bit dependent on which of the two paths in which the photon is detected. It is too low for many applications. A practical highspeed quantum random number generator based on the measurement of the timing of singlephoton detection relative to an external time reference is proposed and realized. The distribution of the raw data is uniform and the raw random bit rate can reach 109Mbps. However, the rate is still not high enough for some applications such as highspeed quantum key distribution (QKD) system. A 68Gbps quantum random number generator by measuring laser phase fluctuations is implemented. The laser phase fluctuations are converted to intensity by a very stable interferometer where active feedback instead of common temperature control is developed to meet the requirement of stability. The the intensity is measured by a highspeed photodetector and then digitalized to raw data with a rate of 80Gbps. By modeling the system, the minentropy which is used to quantify the quantum randomness of the raw data can be evaluated. After Toeplitzmatrix hashing randomness extraction, the final bit rate can reach 68Gbps. However, for a practical QRNG, the speed bottleneck lies on the speed of randomness extraction, which usually is very slow. To close the gap, a pipeline extraction algorithm based on Toeplitz matrix hashing is proposed and implemented in a highspeed fieldprogrammable gate array (FPGA). Further, all the QRNG components are integrated into a compact module. The final generation rate of the QRNG module with realtime extraction and transmission can reach 3.2Gbps. The series of research progress shows that highspeed quantum random number generators are ready for practical usage.

Key words: quantum random number generator, single-photon detection, min-entropy, laser phase fluctuations, Toeplitz-matrix, randomness extraction

摘要： 量子随机数发生器是一种从量子系统中提取量子力学固有不确定性并输出真随机数的一种仪器或者装置．最常见的一类量子随机数发生器根据光子经过一个分束器后的路径选择来产生随机数，其速率很低，无法满足大多数应用的需求.为了提高速率，提出并实现了一个实用且高速的基于光子相对于外部固定参考的到达时间的量子随机数发生器方案，其原始随机数据符合均匀分布，原始比特率达到了109Mbps.然而，对于某些应用场景，比如高速量子密钥分发系统，这个速率依然不够高.为了满足对超高速率的需求，实验实现了速率高达68Gbps的基于激光相位波动测量的量子随机数发生器方案.激光相位波动被干涉仪转化成亮度信息被高速光电探测器探测，然后量化为产生速率为80Gbps的原始随机数.为了满足干涉仪稳定性的需求，使用主动反馈技术代替了传统的温度控制来实现相位稳定控制.通过对系统建模分析，估算出原始数据中的量子随机性，经过Toeplitz矩阵提取之后得到最终的量子随机数，产生速率可以达到68Gbps.然而，对于一个实用的量子随机数发生器，速率的瓶颈在于非常低的随机性提取速率.为了关闭这个间隙，提出并在高速FPGA中实现了基于Toeplitz矩阵的流水线式的随机性提取算法.同时QRNG的所有组成部分被集成到一个紧凑的模块中.这个包括实时后处理与实时传输的QRNG模块，其最终的比特率达到了32Gbps.这一系列的研究进展表明高速量子随机数发生器已经走向了实用化进程.

关键词: 量子随机数发生器, 单光子探测, 最小熵, 激光相位波动, Toeplitz矩阵, 随机性提取