Measuring randomness with periodic media

We show that the sensitivity to disorder of certain physical properties of periodic media depends on whether the disorder is truly random or not. This allows to utilize periodic media for testing sequences of random numbers and to quantify their departure from true randomness via simple transmission and/or reflection data analysis. This physics-based model shows promises for device applications to test random data.     

Effects of randomness on chaos and order of coupled logistic maps

Natural systems are essentially nonlinear being neither completely ordered nor completely random. These nonlinearities are responsible for a great variety of possibilities that includes chaos. On this basis, the effect of randomness on chaos and order of nonlinear dynamical systems is an important feature to be understood. This Letter considers randomness as fluctuations and uncertainties due to noise and investigates its influence in the nonlinear dynamical behavior of coupled logistic maps. The noise effect is included by adding random variations either to parameters or to state variables. Besides, the coupling uncertainty is investigated by assuming tinny values for the connection parameters, representing the idea that all Nature is, in some sense, weakly connected. Results from numerical simulations show situations where noise alters the system nonlinear dynamics.     

Improved quantum randomness amplification with finite number of untrusted devices based on a novel extractor

Quantum randomness amplification protocols have increasingly attracted attention for their fantastic ability to amplify weak randomness to almost ideal randomness by utilizing quantum systems. Recently, a realistic noise-tolerant randomness amplification protocol using a finite number of untrusted devices was proposed. The protocol has the composable security against non-signalling eavesdroppers and could produce a single bit of randomness from weak randomness sources, which is certified by the violation of certain Bell inequalities. However, the protocol has a non-ignorable limitation on the minentropy of independent sources. In this paper, we further develop the randomness amplification method and present a novel quantum randomness amplification protocol based on an explicit non-malleable two independent-source randomness extractor, which could remarkably reduce the above-mentioned specific limitation. Moreover, the composable security of our improved protocol is also proposed. Our results could significantly expand the application range for practical quantum randomness amplification, and provide a new insight on the practical design method for randomness extraction.     

超声微研磨装置的研制

气缸工作表面必须生成储油结构。在缸套工作表面原已形成数以万计、相互独立、深度一致的微坑，在此基础上，本文使用超声微研磨方法再形成一些细小的、不均匀分布的微细沟槽或点坑，以形成复合储油结构。文章提出了超声微研磨方法，设计了超声微研磨装置，测量了超声换能器的谐振频率，为工业化试验和应用奠定了基础。     

Contact barriers in a single ZnO nanowire device

The contact potential between a single ZnO nanowire and Ti/Au contacts was estimated to be ∼30 meV by considering the Arrhenious plot of the two-probe resistance, the thermionic emission conduction, and the Fowler–Nordheim tunneling model. The net voltages applied to the contacts were calculated by subtracting the four-probe voltages from the two-probe voltages at the same currents. The activation energy of the four-probe resistance was about 2.4 mV which was 1/11th of that of the two-probe resistance. The Fowler–Nordheim plot clearly showed the crossover of the conduction mechanism from thermionic emission to tunneling regime as lowering the temperatures below T<100 K.     

光学单池中受激布里渊散射的双光束共轴放大

介绍了一种在单池中实现受激布里渊散射双光束共轴放大的方法,能够在单一光学池中同时实现受激布里渊散射的产生和放大.相比于传统的双池放大技术,这种方法具有结构简单、信号损失小的优点.对于激光雷达等无法采用双池放大的实际应用领域,单池放大技术更是一种必要的方法. 关键词： 受激布里渊散射 放大 光学单池     

Parasitic bipolar amplification in a single event transient and its temperature dependence

Using three-dimensional technology computer-aided design (TCAD) simulation, parasitic bipolar amplification in a single event transient (SET) current of a single transistor and its temperature dependence are studied. We quantify the contributions of different current components in a SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both 130-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of the SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of a single transistor.     

EAST装置内置低温冷凝泵低温分配阀箱的研制

在全超导磁约束核聚变试验装置EAST中,为了防止杂质从偏虑器靶板附近进入等离子体核心,为EAST长脉冲放电试验提供持续的排灰能力以及装置长冲放电等,低温冷凝泵是必不可少的部件之一,在装置真空室上下安装了内置低温凝泵以提高装置运行参数,为满足低温泵的低温条件,增加一低温分配阀箱给内置低温冷凝泵提供低温条件。文中介绍应用于EAST装置系统中的内置低温冷凝泵分配阀箱研制的技术要求、冷却流程、结构特征。     

Dynamics and scaling in a quantum spin chain material with bond randomness

Single crystal inelastic neutron scattering is used to study dynamic spin correlations in the quasi-one-dimensional quantum antiferromagnet BaCu2(Si0.5Ge0.5)2O7, where the exchange constant fluctuates due to a random distribution of Si and Ge atoms. The measured low-energy spectrum is dominated by localized excitations and can be understood in the framework of the random singlet model. The observed scaling relations for the frequency dependencies of the correlation length and structure factor are in excellent agreement with recent theoretical predictions for the renormalization group fixed point.     

用于射频超导量子干涉器的新型单CSRR磁通聚焦器和谐振器

文提出了一种新型磁通聚焦器和谐振器. 磁通聚焦器引入了单互补开环谐振器结构 (单CSRR); 谐振器则采用环绕着绕磁通聚焦器的发夹型3阶阶梯阻抗谐振器 (SIR). 采用ANSYS HFSSv.11高频结构仿真软件对提出的磁通聚焦器和谐振器进行了仿真, 并对单CSRR进行了理论分析. 仿真和理论分析表明: 单CSRR的引入, 提高了磁通聚焦器的聚磁效果, 改善了磁通聚焦器与RF SQUID垫圈的耦合(耦合系数k_sc为引入单CSRR前的2倍), 并且有效面积增大到1.227 mm².     

单粒子瞬变中的双极放大效应研究

采用三维数值模拟的方法对比研究了单个NMOS晶体管和反相器链中的单粒子瞬变（single event transient,SET）电流脉冲,发现深亚微米工艺下双极放大电流在单管的SET电流脉冲中占主要成分,而在反相器链的SET模拟中不明显,分析二者的区别解释了源/体结偏压的形成过程和放大机理,并证明了双极放大效应受源/体结偏压影响的结论.在此基础上分析了NMOS管中源极的正向电流及其机理,发现台阶区的源极正向电流主要是由扩散作用形成的. 关键词： 单粒子瞬变 双极放大 混合模拟 台阶区电流     

Chirped pulse amplification in single mode Tm:fiber using a chirped Bragg grating

We report femtosecond pulse generation and chirped pulse amplification in Tm:fiber. A mode-locked oscillator operating in the soliton regime produced 800 fs pulses with 5 nm spectral bandwidth, at 40 pJ pulse energy. This oscillator seeded a pre-amplifier that utilizes a Raman soliton self-frequency shift to produce wavelength tunable pulses with 3 nJ energy, reduced pulse duration of 150 fs, and increased bandwidth of 30 nm. For further amplification, the pulses were stretched up to 160 ps using a chirped Bragg grating (CBG). Stretched pulses were amplified to 85 nJ after compression in single-mode Tm:fiber and recompressed with the CBG as short as 400 fs. Compressed pulses were coupled into a highly nonlinear tellurite fiber to investigate the potential of this ultrashort pulse 2-μm fiber source as a pump for mid-IR supercontinuum generation.     

Gain and gain-flatness improved photonic crystal fiber Raman amplifier based on a dual-pass amplification configuration with single pump laser

A gain and gain-flatness improved L-band dual-pass Raman fiber amplifier (RFA) utilizing a photonic crystal fiber (PCF) as gain medium is demonstrated. By introducing complementary gain spectra of typical forward and backward pumping single-pass RFA using the same PCF, we finally achieve average net gain level of 22.5 dB with a ±0.8 dB flattening gain in 20-nm bandwidth from 1595 nm to 1615 nm, which is rare in RFAs with only one single pump and no flattening filter. Compared with the single-pass pump configurations, gain level, flatness and bandwidth are greatly improved by using the dual-pass amplification configuration. The limitation of this configuration caused by multi-path interference (MPI) noise and stimulated Brillouin scattering (SBS) is also discussed.     

Resonant amplification of frustrated evanescent waves by single dielectric coating

Resonant amplification and enhancement of evanescent wave’s frustration across an optical barrier by using single dielectric coating is numerically demonstrated in this article. With further tuning of the thickness values of the second and the third medium (optical barrier) of the proposed stratified four-media configuration, it is shown that it may be possible to achieve unity transmittance at discrete, but closely spaced incident angles within the full range defined by the theoretical cut-off limit. The designed configuration may have other potential applications than lithography and waveguide design is one such example.     

Amplified spontaneous emission in dye-laser systems for single photon amplification

A longitudinally pumped dye-laser amplifier is numerically investigated for the amplification of a very low intensity signal (as low as one photon per pulse), which is easily hindered by the simultaneous amplification of spontaneous emission. From the relevant set of coupled rate equations for population and photon fluxes the spatial dependence of these quantities is accounted for. The equations are solved numerically in some significant practical situations. The results describe the dependence of the amplified-spontaneous-emission (ASE) output flux on the pumping rate, on the spectral narrowing process and on the total spontaneous emission for a pulse in the selected angular width. The performance of dye-laser amplifiers is described by the same set of equations, and the gain characteristics of such systems are analyzed as functions of the pumping rate.     

Scalable spin amplification with a gain over a hundred

We propose a scalable and practical implementation of spin amplification which does not require individual addressing nor a specially tailored spin network. We have demonstrated a gain of 140 in a solid-state nuclear spin system of which the spin polarization has been increased to 0.12 using dynamic nuclear polarization with photoexcited triplet electron spins. Spin amplification scalable to a higher gain opens the door to the single spin measurement for a readout of quantum computers as well as practical applications of nuclear magnetic resonance spectroscopy to infinitesimal samples which have been concealed by thermal noise.     

基于单电子器件的混沌电路研究

利用单电子晶体管和金属氧化物半导体的混合器件——SETMOS设计实现了细胞神经网络结构的蔡氏电路,得到了单涡卷吸引子和双涡卷吸引子.通过设计构成的SETMOS跨导放大器和SETMOS电压比较器,提出了基于SETMOS的类双涡卷混沌电路,仿真验证了类双涡卷吸引子.模拟结果表明,所设计的硬件电路结构简单,功耗低,有利于进一步提高集成电路的集成度,为混沌在工程领域的实际应用提供了新方法. 关键词： 细胞神经网络 蔡氏电路 混沌 涡卷     

Tunable nano Peltier cooling device from geometric effects using a single graphene nanoribbon

Based on the phenomenon of curvature-induced doping in graphene we propose a class of Peltier cooling devices, produced by geometrical effects, without gating. We show how a graphene nanorib- bon laid on an array of curved nano cylinders can be used to create a targeted and tunable cooling device. Using two different approaches, the Nonequilibrium Green＇s Function （NEGF） method and experimental inputs, we predict that the cooling kW/cm2, on par with the best known techniques power of such a device can approach the order of using standard superlattice structures. The structure proposed here helps pave the way toward designing graphene electronics which use geometry rather than gating to control devices.