基于单光子脉冲时间随机性的光量子随机源

提出了一种基于单光子脉冲时间随机性的光量子随机源。利用衰减成单光子态的光强恒定光源和一个单光子探测器产生单光子随机脉冲,通过连续比较单光子随机脉冲序列中相邻两个脉冲的时间间隔来提取随机位。通过设计高速响应的微通道板单光子探测器和基于现场可编程门阵列(FPGA)的随机位提取电路,获得了超过10Mbit/s的随机位产生速率。通过采用恒比定时和对计数时钟倍频的方法提高时间间隔的测量精度,从而减小随机位序列的相关系数。当光量子随机源的随机位产生速率在10kbit/s以下时,所获得的二进制随机位序列的相关系数小于0.001。运用随机性测试程序ENT和DIEHARD对所获的随机位序列进行测试,测试结果表明序列的随机性非常好且不需要后续处理,完全满足真随机数的标准。     

等时间间隔内光子数奇偶随机性的光量子随机源

提出一种基于等时间间隔内光子数奇偶随机性光量子随机源.将连续波激光二极管发射的光衰减成离散的单光子序列,利用雪崩光电二极管单光子探测模块来探测光子,通过测量等时间内探测到光子数的奇偶性来提取随机位.研制出了基于现场可编程门阵列的随机位提取电路,测试和分析了时间间隔大小和单光子计数模块的性能参量对所设计随机源提取随机数性能的影响.根据系统平均计数率自动设置时间间隔大小,实现了偏差小、速度快的随机位产生器.所设计随机源工作在计数率为20 Mcps,时间间隔设置为0.5μs时,可获得2 Mbit/s的随机位产生速率.运用随机性检测包ENT和STS对所获得的随机位序列进行测试,表明序列的随机性满足真随机数标准,不需要后续处理.     

光量子随机数发生器

设计制作了基于单光子量子随机性的二进制随机数发生器,通过50/50光分束器的光子流被其后的单光子探测器记录下光子路径,经高速电路和计算机数据采集系统转换为二进制随机数流,目前实验中随机数采集速率达100 Kbit/s,本文采用延迟符合计数法来克服探测器暗计数的影响.使暗计数对随机数序列的影响下降了2到3个数量级,最后应用的三种随机性测试表明所采数据随机性良好.     

基于光子间隙随机分布的任意进制真随机数源

根据激光光子数的泊松分布特征，通过衰减脉冲激光的光强度使衰减后平均每十个脉冲含有一个光子，该光子在十个脉冲中位置的分布是随机的，也即任意二十个脉冲中的两个光子的间隙时间是随机的。基于该随机间隙时间可产生真随机数序列，不仅可以产生二进制随机数，也可产生多进制的。实验上分别制备了二进制和十进制真随机数序列；对数据量为100M的样本进行通用的ENT程序随机性检验，检测结果很好。此外，该实验方案具有抗干扰能力强、便于集成、随机数产生速率容易提高等优点，可广泛应用于保密通信、身份验证、Monte Carlo计算、彩票游戏等领域。     

基于光子间隙随机分布的真随机数源

提出了利用模数转换器提高真随机数源速率的方案, 该方案基于衰减脉冲激光光子间隙随机分布, 可使随机数的产生速率提高十几倍.实验中将时间幅度转换仪与16位模数转换器相结合, 产生的各比特位随机数序列顺利通过了国际通用的随机数检测程序统计测试标准, 该方案实验装置简单, 增强了系统的抗干扰能力. 关键词： 衰减式单光子源 模数转换 延时符合 随机数检测     

偏振光量子随机源

报道了一种基于偏振光量子的随机效应产生的随机源，这种方法利用了单个偏振光子在偏振分束镜表现出来的量子随机性.用同步符合单光子检测技术，对衰减的偏振单光子源在偏振分束镜表现的随机性进行检测，利用计算机和数据采集卡，获得了二元随机码.利用国际通用的随机数检测程序(ENT)对直接获得的数据进行随机性分析，结果完全满足真随机数的标准.     

一种全光纤型观测光波粒二象性的方法

提出一种结构简单、实验现象明显的光波粒二象性观测方案,本方案以波的相干叠加突出显示光的波动性,以粒子在50/50分束器的路径随机选择特性突出显示光的粒子性.以衰减强激光脉冲为光子源,在实验室获得的干涉对比度超过99%,单粒子特性超过90%.实验结果表明此方案有望在实际得到广泛应用.     

基于单光子的单向量子安全通信协议

提出了基于单光子的单向量子安全通信方案.发送方在对信息序列进行编码操作之前首先将其和随机序列进行异或操作并插入校验序列.接收方收到光子后对其进行延迟,此后发送方公布编码基从而使接收方在正确的基下进行测量.接着双方通过校验序列判断信道的安全性,如果信道安全,则发送方公布接收方有测量结果的位置所对应的随机序列,接收方由此恢复出信息序列;如果信道不安全,窃听者所获得的只是随机的发送序列,信息序列仍然是安全的.此协议与双向通信协议相比具有传输效率高、 易于实现等优点. 关键词： 量子密码 量子安全通信 单光子 单向通信     

基于色散位移光纤的高宣布式窄带单光子源

文章利用脉冲激光抽运色散位移光纤,通过自发四波混频过程产生的关联光子对,实验演示了一种光通讯波段的窄带宣布式单光子源. 实验测得-3 dB带宽为1.1 nm单光子场的二阶关联函数g⁽²⁾(0)=0.09±0.01,宣布效率可达0.5以上. 这种单光子源在量子通信中有潜在的应用前景. 关键词： 宣布式单光子 光纤 自发四波混频 量子通信     

长距离长期稳定的量子密钥分发系统

介绍了最近完成的长距离长期稳定的量子密钥分发系统.该系统利用往返光路补偿光纤偏振 抖动和相位漂移的原理,采用结电容平衡魔T网络耦合的单光子探测技术,在506km单模 光纤中实现了长时间（大于12h）稳定的量子密钥分发实验.单脉冲平均光子数为007, 误码率为4%,其中单光子探测器的探测效率大于5%,单脉冲暗计数低于29×10^{-6. 关键词： 量子保密通信 量子密钥分发 单光子探测}     

Magnetic properties of xFe2O3(1−x)[B2O3 · PbO] glasses

The magnetic measurements performed on xFe₂O₃(1-x)[B₂O₃ · PbO] glasses show that for x 5 mol.% Fe₂O₃ the thermal variation of reciprocal susceptibility obeys a Curie behaviour. For higher iron content, at T 50 K, a nonlinear variation, typical for systems with random distribution of exchange interactions is observed. At greater temperatures than 50 K a Curie-Weiss behaviour is shown. The composition dependence of the Curie constants is analysed in correlation with the number of Fe³⁺ and Fe²⁺ ions as determined from Mössbauer effect measurements. A comparison with the data obtained in case of xFe₂O₃(1-x)[3B₂O₃ · PbO] glasses is made.     

Superfluorescence from Small Samples

The initiation of superfluorescence from N ≦ 70 atoms distributed randomly over the volume of a sphere is investigated by numerical computations. When a specified atomic configuration is changed by performing similarity transformations the cooperation number approaches an asymptotic value ? 1 for mean distances ? λ/50. This number does not depend on inhomogeneous broadening but sensitively depends on the specified random distribution of atoms. The mean value of the asymptotic cooperation number calculated for many configurations is near to √N.     

Ticks of a Random clock

A simple way to convert a purely random sequence of events into a signal with a strong periodic component is proposed. The signal consists of those instants of time at which the length of the random sequence exceeds an integer multiple of a given number. The larger this number the more pronounced the periodic behavior becomes.     

Physical generation of random numbers using an asymmetrical Boolean network

Autonomous Boolean networks (ABNs) have been successfully applied to the generation of random number due to their complex nonlinear dynamics and convenient on-chip integration. Most of the ABNs used for random number generators show a symmetric topology, despite their oscillations dependent on the inconsistency of time delays along links. To address this issue, we suggest an asymmetrical autonomous Boolean network (aABN) and show numerically that it provides large amplitude oscillations by using equal time delays along links and the same logical gates. Experimental results show that the chaotic features of aABN are comparable to those of symmetric ABNs despite their being made of fewer nodes. Finally, we put forward a random number generator based on aABN and show that it generates the random numbers passing the NIST test suite at 100 Mbits/s. The unpredictability of the random numbers is analyzed by restarting the random number generator repeatedly. The aABN may replace symmetrical ABNs in many applications using fewer nodes and, in turn, reducing power consumption.     

Random crystal field effect on hysteresis loops and compensation behavior of mixed spin-(1, 3/2) Ising system

Magnetic hysteresis and compensation behavior of a mixed spin-(1, 3/2) Ising model on a square lattice are investigated in the framework of effective field theory based on a probability distribution technique. The effect of random crystal field, ferromagnetic and ferrimagnetic exchange interaction on hysteresis loops and compensation phenomenon are discussed. A number of characteristic phenomena have been reported such as the observation of triple hysteresis loops at low temperatures and for negative values of random crystal field. Critical and double compensation temperatures have been also found. The obtained results are also compared to some previous works.     

Implementation of a quantum random number generator based on the optimal clustering of photocounts

To implement quantum random number generators, it is fundamentally important to have a mathematically provable and experimentally testable process of measurements of a system from which an initial random sequence is generated. This makes sure that randomness indeed has a quantum nature. A quantum random number generator has been implemented with the use of the detection of quasi-single-photon radiation by a silicon photomultiplier (SiPM) matrix, which makes it possible to reliably reach the Poisson statistics of photocounts. The choice and use of the optimal clustering of photocounts for the initial sequence of photodetection events and a method of extraction of a random sequence of 0’s and 1’s, which is polynomial in the length of the sequence, have made it possible to reach a yield rate of 64 Mbit/s of the output certainly random sequence.     

A hybrid-type quantum random number generator

This paper proposes a well-performing hybrid-type truly quantum random number generator based on the time interval between two independent single-photon detection signals, which is practical and intuitive, and generates the initial random number sources from a combination of multiple existing random number sources. A time-to-amplitude converter and multichannel analyzer are used for qualitative analysis to demonstrate that each and every step is random. Furthermore, a carefully designed data acquisition system is used to obtain a high-quality random sequence. Our scheme is simple and proves that the random number bit rate can be dramatically increased to satisfy practical requirements.     

Random fiber laser operating at 1,115 nm

We experimentally demonstrate a random fiber laser operating at 1,115 nm using a LD-pumped Yb-doped fiber laser as the pump source. We achieve about 270 mW lasing output in a 50 km standard communication optical fiber with slope efficiency more than 28 %. A new wavelength is provided for the application of random distributed feedback fiber lasers as light sources.