强度反馈半导体激光器的量子噪声

本文提出了强度反馈半导体激光器的模型,分析了其量子噪声。分析表明:该半导体激光器的量子AM噪声性能优于普通半导体激光器的AM噪声性能。     

光通讯系统中的背景噪声

在设计光通讯系统时,要考虑的光谱噪声基本有两种:热噪声(亦称琼生噪声)和量子噪声(亦称散粒效应噪声)。热噪声来自探测系统内的负荷电阻和放大器(主要在前端);量子噪声来自探测系统内、外两个部分。在内部产生的量子噪声是由暗电流引起的。由外源产生的量子噪声与入射于     

实虚部关联的量子噪声和抽运噪声对单模激光光强关联函数的影响

采用抽运噪声和实虚部之间关联的量子噪声驱动的单模激光损失模型，运用线性化近似方法计算了反映激光动力学性质的光强关联函数C(t)和光强相对涨落C(0)，讨沦了光强关联函数随时间t的演化，分析了量子噪声实虚部间关联系数λq，抽运噪声强度P和量子噪声强度Q对光强关联函数C(t)随时间t演化过程的影响。发现C(t)随时间t的演化是单调衰减过程，但噪声强度的减小和量子噪声实虚部间关联的减弱会使演化曲线整体下移，说明噪声强度和量子噪声实虚部间的关联对C(t)随时间t的演化过程有较大的影响。当时间t增加时，C(t)与量子噪声实虚部间关联系数λq的关系曲线出现了一个极值和三个极值两种不同的情况。最后分析了线性化近似方法适用的条件。     

面向可靠性的CNOT量子线路最近邻综合

在噪声中等规模量子(NISQ)设备上,量子线路可靠性受到量子噪声的影响。为了实现CNOT量子线路在量子芯片上高效可靠的执行,以相邻量子位交互错误率为权重,给出了计算最小Steiner噪声路径长度的代价度量方法,提出了噪声感知的CNOT量子线路最近邻综合算法。实验结果表明,与现有方法相比,所提出的综合算法在保证线路可靠性的前提下,有效地降低了综合过程中所使用CNOT门的数量, CNOT门代价的平均优化率达到27.7%,其中200门级的CNOT量子线路优化率达到了93.79%。     

半导体激光器动态量子AM和FM噪声的理论

本文用小信号分析的方法,研究了当对半导体激光器(LD)进行直接调制时(动态)LD的量子噪声,首次给出了LD的动态AM与FM噪声谱的解析表达式.分析表明,调制强度与调制频率均对LD的量子噪声有极大的影响.     

量子反馈控制研究进展

量子反馈控制理论将反馈的思想引入量子系统的主动控制中,已开始在量子光学、原子物理和量子信息学等领域发挥越来越重要的作用.考虑到各种反馈策略的差异性,综述了量子反馈控制理论的研究进展,分析和阐述了马尔可夫量子反馈、贝叶斯量子反馈、含时延非马尔可夫量子反馈和相干量子反馈,并对四种量子反馈策略进行了简单比较.     

量子色噪声对单模激光场的影响

单模激光的统计性质主要由引起激光场涨落的量子噪声和抽运噪声决定.人们通常假设抽运噪声为色噪声,而量子噪声为白噪声.白噪声只是一种理想模型,本文将两类噪声均模拟为更接近于实际情况的O-U色噪声,研究色噪声尤其是量子色噪声效应. 单模激光增益模型的光强朗之万方程为: (dI)/(dt)=-2kI+(2ΓI)/(1+βI)+D+(2I)/(1+βI)ξ(t)+2Iq(t) 式中,ξ(t)为抽运噪声,q(t)为量子噪声,是自关联时间分别为τ1和τ2的O-U色噪声.应用线性化近似方法,得到了光强的关联函数、功率谱以及含时矩的解析表达式,结果分析表明: 1) 抽运噪声和量子噪声的自关联时间τ1和τ2越大,光强的相对涨落λ(o)越小,表明色噪声使得线性化近似的适用范围扩大; 2) 光强关联函数λ(t)的初始斜率limt→0[dλ(t)/dt]=0,这一结果与白噪声情形显著不同,表明λ(t)出现初始平台现象的根源在于色噪声; 3) λ(t)随时间t的增加而衰减,随着τ2的增加,λ(t)的衰减被延缓,即量子色噪声将增加激光系统的统计涨落; 4) 光强功率谱为单峰,τ2对峰值频率和峰高均没有影响,但随着τ2的增加,S(ω)的峰形越来越尖锐; 5) 协方差K2(t)随时间t的增加而增大,说明K2(t)在较短的时间内达到饱和,随着τ2的增加,K2(t)减少,即K2(t)达到饱和的时间延长.(PA2)     

基于SVM的量子线路输出校准方法研究

当前噪声中尺度量子(NISQ)计算机由于受到各种噪声的影响,量子线路运行结果和理想结果之间存在误差,因此需要对量子线路的运行结果进行校准。基于量子线路可逆性的特点,收集正反向线路运行数据中的状态误差作为主要噪声特征,提出了基于支持向量机(SVM)集成策略的输出校准方法。通过支持向量机-递归特征消除（SVM-RFE）方法对噪声特征进行排序,去除过拟合的特征,从而得到更优的量子线路输出校准结果。实验结果表明,与基于优化映射的方法相比,所提基于SVM的方法使量子线路输出结果更接近于理想结果,与基于决策树集成分类模型（Qraft）相比,当CNOT量子线路的门数为60时,改善率达到43.94%。     

直接耦合半导体光放大器的噪声特性

研究了直接耦合混合应变量子阱半导体光放大器(SOA)的噪声特性.实验中测定SOA在130 mA偏置电流下的噪声指数为7.7 dB,表明应变量子阱结构改善了SOA的噪声性能.理论分析指出,通过消除SOA的剩余反射,其噪声性能可以得到进一步改善.     

利用孪生光束实现强度量子关联的传递

利用两个相互独立的非简并光学参量振荡器(NOPO)产生的两对强度量子关联孪生光束,在实验上成功实现了多光束间量子关联的传递,使两束毫无关联的独立光束产生了强度差噪声低于散粒噪声基准0.8 dB的量子关联.     

Noise measurements in charge-coupled devices

Measurements of the noise levels at the output of surface and bulk channel charge-coupled devices with three-phase overlapping polysilicon electrodes are presented. Pulser noise, correlated transfer noise, shot noise, dark current noise, and electrical insertion noise at the input have been measured and studied. The dependences of the electrical insertion noise and the transfer noise on charge packet size and clock frequency are discussed in detail and the latter related to interface state densities. New schemes and input circuits for low-noise electrical insertion of the signal charge are discussed. Our measurements indicate that the noise levels due to the intrinsic noise sources (transfer and storage noise) agree with our physical understanding of the device operation. The noise levels due to the extrinsic noise sources (pulser noise and electrical insertion noise) are above the expected theoretical values.     

Investigation of Thermal Noise in UTB GOI and SOI Devices

The thermal-noise performances of ultrathin-body silicon-on-insulator (SOI) and germanium-on-insulator (GOI) devices are investigated and compared through simulation in this paper. The figures-of-merit for noise characteristics are considered in terms of the minimum of noise figure (NF_min)and equivalent noise resistance (R_n). GOI devices exhibit better noise performance over SOI counterparts. The reduction in the supply voltage brings more distinct improvements of the noise performance of GOI devices. The dependence of noise parameters on the film thickness and spacer length is also analyzed. The results demonstrate that GOI devices are more suitable for RF and low-noise applications.     

Noise analysis of an amplified fiber-optic recirculating-ring delayline

We present the first theoretical and experimental noise analysis of a fiber-optic recirculating-ring delay line (RDL) including a doped fiber amplifier to compensate for the roundtrip loss. Both thermal-like sources and laser sources are considered. The output source induced noise (signal-signal beat noise), signal-spontaneous (s-sp) beat noise, and spontaneous-spontaneous (sp-sp) beat noise spectra for a thermal-like source are calculated from the autocorrelation function of the output detector current. It is shown that all three electrical beat noise spectra can be expressed as correlations of the output optical signal and ASE spectra. The source-induced noise will normally be the dominating noise source, but in some applications, the other noise terms also will be of importance. We use our theory to define the maximum number of recirculations in an amplified RDL with a pulsed source, where the fundamental noise floor is determined by the sp-sp beat noise     

The visibility of noise in System I PAL colour television

The results of new subjective tests on the visibility of noise in System I PAL colour television are reported. Three forms of noise are considered: white (flat) noise, de-emphasised triangular noise, and the noise resulting from vestigial sideband demodulation (VSB noise). The results are compared with those given by work published 20 years ago and it is concluded that observers today are more critical of noise in pictures: about 2¹/₂ dB less noise is required to produce the same impairment     

Performance of DRA with different pumping schemes based on coupling equation

After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others’.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.     

相位噪声对单/双基地SAR积累的影响

在相位噪声理论模型的基础上,推导出反映相位噪声导致的相参积累损失因子和信噪比.结合单/双基地合成孔径雷达(SAR)的信号收发关系,给出了单/双基地条件下回波相位噪声的关系式,并以典型机载SAR参数进行相噪对聚焦性能的仿真分析.结果表明,相位噪声对双基地SAR的影响明显大于单基地.该分析方法也可应用于其他类型相参雷达的积累性能分析.     

MIMU随机误差分析与建模

分析了MEMS惯性测量组件(MIMU)的主要误差源,采用功率谱密度(PSD)法和Allan方差法对MIMU进行了随机误差分析、建模和估计研究。将随机误差中的量化噪声、闪烁噪声及随机游走噪声等误差成分分离出来,并对其统计特性进行了估计,实验数据分析表明闪烁噪声和随机游走误差在MIMU随机误差中占主要分量。     

Design and noise analysis of a sigma-delta capacitive micromachined accelerometer

A single-loop fourth-order sigma-delta (∑△) interface circuit for a closed-loop micromachined accelerometer is presented.Two additional electronic integrators are cascaded with the micromachined sensing element to form a fourth-order loop filter.The three main noise sources affecting the overall system resolution of a ∑Δ accelerometer,mechanical noise,electronic noise and quantization noise,are analyzed in detail.Accurate mathematical formulas for electronic and quantization noise are established.The ASIC is fabricated in a 0.5 μm two-metal two-poly n-well CMOS process.The test results indicate that the mechanical noise and electronic noise are 1 μg(Hz) and 8 μV/(Hz)respectively,and the theoretical models of electronic and quantization noise agree well with the test and simulation results.     

Dynamic denoising studies in wideband radio channel measurement and modeling

The fixed level and dynamic denoising method was studied based on indoor-to-outdoor measured channel impulse responses ORs） at 5.25 GHz with radio frequency （RF） 100 MHz bandwidth. It is found that the dynamic ranges, peak powers and noise floors of the IRs are with close correlations. The comparisons with different denoising methods are given by deriving the power delay profiles （PDPs）, root mean square （RMS） delay spread （RMS DS）, number of paths （NOPs） and Ricean K-factors. It is concluded that the traditional fixed level noise cut is under estimate of DS and NOPs. The Ricean K-factors are of little sensitive to noise cut irrespective of what kind of methods applied. The PDPs are not very sensitive to the fixed level noise cut, however, obvious changes can be found by dynamic noise cut. The dynamic noise cut is preferred when clear noise floors is observed and decided from the measured IRs, it＇s of importance in data post processing for wideband radio channel measurements as well as the relevant modeling work.     

Signature of Man-Made High-Frequency Radio Noise

This paper expands the single sloping line labeled ?man-made noise? in existing atmospheric radio noise predictions. Data taken from the Puget Sound (Seattle) area are developed to show spectral (0.1-10 MHz) and spatial (1-100 miles) man-made radio noise distributions. The effects of soil/saltwater conductivity contrasts and receiver elevation above ground are also considered. Methods of predicting noise contributions from both nearby cities and electric trunk lines are presented.