A Comprehensive Analysis for Eight Formulas for Rotational Spectra

All the data now available for the ground rotational bands of actinide even-even nuclei and rare-earth even-even nuclei are analyzed with eight formulas for rotational spectra.It can be seen from calculated results that the four-parameter I(I+1) expansion,the four-parameter ω² expansion and W-Z formula can fit the GRB's of well-deformed unclei very well.     

Quantum Scars in Microwave Dielectric Photonic Graphene Billiards

In the band structure of graphene,the dispersion relation is linear around a Dirac point at the corners of the Brillouin zone.The closed graphene system has proven to be the ideal model to investigate relativistic quantum chaos phenomena.The electromagnetic material photonic graphene(PG) and electronic graphene not only have the same structural symmetry,but also have the similar band structure.Thus,we consider a stadium shaped resonant cavity filled with PG to demonstrate the relativistic quantum chaos phenomenon by numerical simulation.It is interesting that the relativistic quantum scars not only are identified in the PG cavities,but also appear and disappear repeatedly.The wave vector difference between repetitive scars on the same orbit is analyzed and confirmed to follow the quantization rule.The exploration will not only demonstrate a visual simulation of relativistic quantum scars but also propose a physical system for observing valley-dependent relativistic quantum scars,which is helpful for further understanding of quantum chaos.     

Quantum Scars in Microwave Dielec trie Photonic Graphene Billiards

Brillouin zone.The closed graphene system has proven to be the ideal model to investigate relativistic quantum chaos phenomena.The electromagnetic material photonic graphene(PG)and electronic graphene not only have the same structural symmetry,but also have the similar band structure.Thus,we consider a stadium shaped resonant cavity filled with PG to demonstrate the relativistic quantum chaos phenomenon by numerical simulation.It is interesting that the relativistic quantum scars not only are identified in the PG cavities,but also appear and disappear repeatedly.The wave vector difference between repetitive scars on the same orbit is analyzed and confirmed to follow the quantization rule.The exploration will not only demonstrate a visual simulation of relativistic quantum scars but also propose a physical system for observing valley-dependent relativistic quantum scars,which is helpful for further understanding of quantum chaos.     

Noise Corrections to Stochastic Trace Formulas

We review studies of an evolution operator for a discrete Langevin equation with a strongly hyperbolic classical dynamics and a Gaussian noise. The leading eigenvalue of yields a physically measurable property of the dynamical system, the escape rate from the repeller. The spectrum of the evolution operator in the weak noise limit can be computed in several ways. A method using a local matrix representation of the operator allows to push the corrections to the escape rate up to order eight in the noise expansion parameter. These corrections then appear to form a divergent series. Actually, via a cumulant expansion, they relate to analogous divergent series for other quantities, the traces of the evolution operators ⁿ. Using an integral representation of the evolution operator , we then investigate the high order corrections to the latter traces. Their asymptotic behavior is found to be controlled by sub-dominant saddle points previously neglected in the perturbative expansion, and to be ultimately described by a kind of trace formula.     

Sinai Billiards, Ruelle Zeta-functions and Ruelle Resonances: Microwave Experiments

We discuss the impact of recent developments in the theory of chaotic dynamical systems, particularly the results of Sinai and Ruelle, on microwave experiments designed to study quantum chaos. The properties of closed Sinai billiard microwave cavities are discussed in terms of universal predictions from random matrix theory, as well as periodic orbit contributions which manifest as scars in eigenfunctions. The semiclassical and classical Ruelle zeta-functions lead to quantum and classical resonances, both of which are observed in microwave experiments on n-disk hyperbolic billiards.     

Properties of IR Absorption Spectra of Bi-Pb-Sr-Ca-Cu-O Superconducting Material

Abstract

We used the co-decomposition method to make the Bi(Pb)-Sr-Ca-Cu-O superconductor samples (T_c = 112K) under oxygen partial pressure. Oxygen dependence of high-T_c phase was studied. The infrared absorption spectra of (Bi_1?xPb_x)₂Sr₂Ca₂Cu₃O_10+σ superconductor were measured at various temperatures from 98 to 290K. A new IR absorption peak was observed at 1265 cm^?1 below 217K. The intensity of this peak became stronger with temperature decreasing.     

集成滤波器结构的可调超导微波谐振腔

在超导微波谐振腔耦合量子比特的杂化器件中,可利用超导材料动态电感随直流电流变化的特性,调节谐振腔的频率,进而匹配量子比特的频率.为抑制引入直流偏置电极导致的微波信号泄漏,在可调腔中加入滤波器是一种有效的方案.本研究以滤波器为切入点,运用计算机模拟,开发了原有“王”字型滤波器新的工作模式,并在实验上制作了可调超导微波谐振腔.测试结果表明,谐振腔的品质因子可达7800,阻抗约1700欧姆,谐振腔的频率可随直流电流发生明显变化,最大变化量可达26 MHz.     

Trace Formulas for Stochastic Evolution Operators: Weak Noise Perturbation Theory

Periodic orbit theory is all effective tool for the analysis of classical and quantum chaotic systems. In this paper we extend this approach to stochastic systems, in particular to mappings with additive noise. The theory is cast in the standard field-theoretic formalism and weak noise perturbation theory written in terms of Feynman diagrams. The result is a stochastic analog of the next-to-leading ? corrections to the Gutzwiller trace formula, with long-time averages calculated from periodic orbits of the deterministic system. The perturbative corrections are computed analytically and tested numerically on a simple 1-dimensional system.     

超导腔垂直测量系统中的磁屏蔽

简要介绍空间磁场对纯铌超导加速腔性能的影响,以及在超导腔垂直测量时对空间磁场进行有效屏蔽的方法.由于多数磁性材料对应力和温度变化非常敏感,而且国内缺乏在低温下相关磁屏蔽材料性能的数据,为此对8种国产铁磁和软磁材料在低温下的初始磁导率进行了测量,并给出了相应的测试结果.最后介绍了作者研制的1.3GHz超导腔垂直测量低温恒温器内置式磁屏蔽装置及其性能.     

Improved Estimates for Correlations in Billiards

We consider several classes of chaotic billiards with slow (polynomial) mixing rates, which include Bunimovich’s stadium and dispersing billiards with cusps. In recent papers by Markarian and the present authors, estimates on the decay of correlations were obtained that were sub-optimal (they contained a redundant logarithmic factor). We sharpen those estimates by removing that factor.     

Limit Theorems for Dispersing Billiards with Cusps

Dispersing billiards with cusps are deterministic dynamical systems with a mild degree of chaos, exhibiting “intermittent” behavior that alternates between regular and chaotic patterns. Their statistical properties are therefore weak and delicate. They are characterized by a slow (power-law) decay of correlations, and as a result the classical central limit theorem fails. We prove that a non-classical central limit theorem holds, with a scaling factor of \({\sqrt{n\log n}}\) replacing the standard \({\sqrt{n}}\) . We also derive the respective Weak Invariance Principle, and we identify the class of observables for which the classical CLT still holds.     

Tunable Microwave Filters Based on Granular Film High-Temperature Superconducting Structures

Microwave filters based on granular high-temperature superconducting structures are studied. Filters with granular kinetic inductance are very sensitive to the changes in temperature, constant magnetic field, and transport current flowing through a high-temperature superconducting film. The tuning sensitivity to temperature, constant magnetic field, and transport current is, on average, 9292 kHz/deg, 185.65 kHz/G, and 26.8 kHz/nA, respectively.     

LLRF超导腔体控制系统的测试

中国科学院近代物理研究所自主研发的ADS注入器Ⅱ第一代高频低电平(LLRF)控制系统,工作频率为162.5 MHz;LLRF系统是由基于I/Q采样的正交解调技术构成的全数字闭环反馈控制系统,其主要功能是实现超导腔腔体电压幅值稳定控制、相位稳定控制与腔体谐振频率控制;LLRF控制系统在液氦温区超导腔上进行了系统稳定度和性能的在线测试,根据实验数据计算得超导腔体电压幅度稳定度为±3.4‰,相位稳定度为±0.3°,腔体表面峰值电场(Epk)能长时间稳定在25.1 MV/m。通过实验测试,检验了LLRF控制系统的性能,并对测试过程中出现的问题进行了分析,为将来超导腔LLRF控制系统运行积累了经验。     

Design of Hyperbolic Billiards

We formulate a general framework for the construction of hyperbolic billiards. Spherical symmetry is exploited for a simple treatment of billiards with spherical caps and soft billiards in higher dimensions. Other examples include the Papenbrock stadium. Reproduction of the entire article for non-commercial purposes is permitted without charge.     

微波与热偏置下超导HEB太赫兹直接检测器的性能比较

本文介绍了一种基于超导氮化铌(NbN)热电子测辐射热计(HEB)的太赫兹(THz)直接检测器,并利用直流读出法和微波反射读出法,对微波与热偏置下HEB直接检测器的性能进行了比较.通过直流读出法,在最佳工作点处,测得微波偏置与热偏置条件下检测器的电流响应率分别为244A/W和20A/W,光学噪声等效功率(NEP)分别为4.5pW/√Hz和6.8pW/√Hz.相比于热偏置,微波偏置能够大大提高检测器的响应率.此外,我们利用微波反射读出法对微波偏置和热偏置下检测器的性能进行了比较.两种读出方式均可很好的表征检测器的性能,而相比于直流读出法,微波反射读出法更易于扩展到多像素阵列,同时具有很快的读出速度,对快速THz脉冲信号的检测具有重要意义.