Lin Jianming, Wang Yonggang, Cao Qiang, Kuang Jie, Wang Liwei
Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China.
Rev Sci Instrum. 2019 Nov 1;90(11):114704. doi: 10.1063/1.5109034.
Silicon photomultiplier (SiPM) arrays normally contain tens of photon detection channels, with each channel consisting of several thousand microcells and each microcell being a normal single-photon avalanche diode with a quenching resistor. The dark counts of SiPM arrays have independent spatial and temporal randomness, which will be used for true random number generation in this paper. Since the arrival times of the high dark count rate in each channel are measured with a fast, high precision time-to-digital converter, along with the number of channels, the entropy can be extracted with very high efficiency. The bias in the raw data due to the exponential distribution of the arrival time differences between successive dark counts is removed using the transformation of the cumulative distribution function. Except for the preamplifiers for a signal readout from a 4-channel SiPM, all electronics components in our prototype are implemented inside of one chip of a field programmable gate array. The prototype has a 63.54 Mbps generation throughput, and the statistical quality of the generated random numbers is evaluated. Since the property of the dark count is compatible with single-photons from laser beams, one can easily increase the generation bitrate by either adding more SiPM channels or irradiating the SiPM with extra laser beams.
硅光电倍增管（SiPM）阵列通常包含数十个光子探测通道，每个通道由数千个微单元组成，且每个微单元都是一个带有猝灭电阻的普通单光子雪崩二极管。SiPM阵列的暗计数具有独立的空间和时间随机性，本文将利用这一特性来生成真随机数。由于每个通道中高暗计数率的到达时间是通过快速、高精度的时间数字转换器测量的，结合通道数量，就能以非常高的效率提取熵。利用累积分布函数的变换消除了原始数据中由于连续暗计数之间到达时间差的指数分布所导致的偏差。除了用于从4通道SiPM读出信号的前置放大器外，我们原型中的所有电子元件都集成在一片现场可编程门阵列芯片内部。该原型的生成吞吐量为63.54 Mbps，并对生成的随机数的统计质量进行了评估。由于暗计数的特性与来自激光束的单光子兼容，因此可以通过增加更多的SiPM通道或用额外的激光束照射SiPM来轻松提高生成比特率。
