Net Voltage and Phenomenon of Resonance Induced by Chaotic Signal for a Superconducting Junctions Device

The effects of a quenched chaotic signal on the over-damped motion of the electron pairs of a superconducting junctions device are studied. It is shown that the chaotic signal can induce the net voltage and the phenomenon of resonance.     

Frequency （Stochastic） Resonance and Stochastic Resonance for a Superconducting Junctions＇ Device

In this paper, we investigate a Josephson-junction device with dichotomous resistance or a special SQUID （superconducting quantum interference device）. It is shown that frequency （stochastic） resonance and stochastic reso- nance can appear for some suitably selected parameters＇ values of the device respectively. Our results can provide some insights for the investigation of the SQUID response to the signal （including the input alternating current, the added al- ternating voltage, the vertically added alternating magnetic field, and the detected （electric-magnetic） temporal-periodic signal）.     

Phenomenon of Resonance in a Two-Mode Laser with an Input Additive Signal

Exact formulas for the power spectrum and signal-to-noise ratio (SNR) with periodic additive signal are calculated in the linear system. Then the phenomenon of resonance is studied in detail. We show that resonance peak and suppressed valley exist in the curves of the SNR versus the coefficient of self-saturation, the net gain and the cross-coupling coefficient of the laser system.     

A Superconducting Quantum Interference Device Measurement System for Ultra Low-Field Nuclear Magnetic Resonance

We describe a superconducting quantum interference device (SQUID)-based nuclear magnetic resonance (NMR) spectrometer operating at ultralow magnetic fields far below the Earth’s field. The spectrometer consists of a helium-cooled magnetic sensor system and two Helmholtz coils, one for pre-polarizing the sample by fields of up to 5 mT, and one for the detection in fields of the nanotesla and microtesla range. The spectrometer represents the current state of the art in ultralow-field NMR and enables the observation of phenomena that are difficult or impossible to achieve by a conventional NMR setting. In particular, one can obtain broad band spectra covering different nuclei, such as ¹H and ³¹P, with a frequency resolution in the millihertz range, observe the variation of their heteronuclear coupling with the detection field strength, and investigate relaxation processes that reflect molecular dynamics in the millisecond range.     

Current Reversal and Negative Conductance for a Super-Conducting Junctions Device

In the paper, we study a super-conducting junctions device subject to an input periodic signal and a constant force. It is shown that, for this device, we can get current reversals for the current of the electron pairs versus the frequency of the periodic signal and negative conductance for the current of the electron pairs as a function of the constant force.     

Colored Noise Induced Net Voltage of the Underdamped Josephson Junction

The underdamped Josephson junction subjected to correlated colored noises was investigated. The results indicated that: (i) There are two critical phenomena in the system; (ii) Net voltage of the system is induced by multiplicative noise, and exhibits non-monotonic behaviors with noise autocorrelation rate and the Josephson junction capacitance.     

超导Josephson结直流I—V特性的数值计算

为了研究超导Josephson结的性质，选用四阶龙格一库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流I-V特性进行了数值计算，并将模拟结果与实验结果进行了比较．     

超导Josephson结直流I-V特性的数值计算

为了研究超导Josephson结的性质,选用四阶龙格-库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流I-V特性进行了数值计算,并将模拟结果与实验结果进行了比较.     

Development of a Frequency Control Device for a Superconducting Half-Wave Resonator

Physics of Atomic Nuclei - The results of mechanical and electrodynamic calculations of a frequency tuner for the half-wave superconducting resonator operating at 325 MHz and a relative speed of...     

Time Delay Induced Stochastic Resonance in One Species Competition Ecosystem without a Periodic Signal

One-species competition ecosystem with noise and time delay was investigated as not driven by a periodic force.The results show that the time delay is responsible for stochastic resonance of the system as delay time is smaller than critical point of the Hopf bifurcation.     

Bosonic Operator Realization of Hamiltonian for a Superconducting Quantum Interference Device

Based on the appropriate bosonic phase operator diagonalized in the entangled state representation we construct the Hamiltonian operator model for a superconducting quantum interference device. The current operator and voltage operator equations are derived.     

Continuous Variable Entanglement of Two Mesoscopic Josephson Junctions Induced by a Thermal Radiation Field

The continuous-variable （CV） entanglement between two mesoscopic Josephson junctions is studied and the time-dependent characteristic function in Wigner representation for the Josephson junction subsystem driven by a singlemode thermal field is analytically obtained. It is found that an initial lowest energy state of the junction subsystem can evolve into a two-mode entangled Gaussian state through the interaction with the thermal radiation field. Furthermore, we investigate the influence of the temperature on the entanglement of the junctions and find that the CV entanglement of the two junctions shows the critical behavior with respect to the temperature.     

Mechanical Analysis and Measurements of a Multicomponent NbTi/Cu Superconducting Magnets Structure for the Fully Superconducting Electron Cyclotron Resonance Ion Source

A fully superconducting electron cyclotron resonance(ECR) ion source(SECRAL Ⅱ) is currently being built in the Institute of Modern Physics,Chinese Academy of Sciences.Its key components are three superconducting solenoids(Nb-Ti/Cu) and six superconducting sextupoles(Nb-Ti/Cu).Different from the conventional superconducting ECR magnetic structure,the SECRAL Ⅱ includes three superconducting solenoid coils that are located inside the superconducting sextupoles.The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids,and the magnets can also be more compact in size.For this multi-component SECRAL Ⅱ generating its self Held of ~8T and being often exposed to the high self Geld,the mechanical analysis has become the main issue to keep their stress at 200 MPa on coils.The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure.To improve the accuracy and efficiency of analysis,according to the composite rule of micromechanics,the equivalent uniform windings are used to simuiate the epoxy-impregnated Nb-Ti/Cu coils.In addition,using low temperature strain gauges and a wireless fast strain acquisition system,a fundamentai experiment on the strains developments of a sextupole is reported.Finally,based on our analysis,the stresses and deformations for its assembly of each SECRAL Ⅱ coil will be further optimized.     

采用超导量子干涉组件在微特斯拉磁场下获取超极化~3He的核磁共振波谱和影像(英文)

该文以超导量子干涉元件研究光激发氦三极化气体的低磁场磁共振与造影术.使用圆偏极化雷色光将氦三气体极化,超导量子干涉元件磁共振与造影之测量是以磁通耦合方式来进行,超导量子干涉元件是用铋锶钙铜氧高溫超导罐来隔离环境噪音.此方法测得的磁共振信号与影像相较于直接将样品置于杜瓦瓶下方有较高的信噪比,当样品无法靠近感测元件时,此装置具高信噪比特色.磁通耦合方式的超导量子干涉元件低磁场磁共振与造影术及其氦三极化气体的肺部造影在学术与应用上是相当有趣.     

Stochastic Resonance in a Time-Delayed Bistable System Driven by Square-Wave Signal

Stochastic resonance in a time-delayed bistable system subject to asymmetric dichotomous noise and multiplicarive and additive white noise is investigated. Using small time delay approximation, we obtain the expression of the signal-to-noise ratio （SNR）. It is found that the SNR is a non-monotonic function of the delayed times, of the amplitude of the input square-wave signal, as well as of the asymmetry of the dichotomous noise. In addition, the SNR varies non-monotonously with the system parameters, with the intensities of the multiplicative and additive noise, as well as with the correlate rate of the dichotomous noise.     

Response of a Superconducting Quantum Interference Device to Alternating Magnetic Field

We study the response of a superconducting quantum interference device （SQUID） to an alternating magnetic field. It is found that, for some suitably selected parameters＇ values, we can obtain stochastic resonance for the amplitude of the steady average voltage of the SQUID versus the dichotomous noise strength, and frequency （stochastic） resonance for the amplitude of the stationary average voltage of the SQUID as a function of the frequency of the alternating magnetic field. Our results can be useful for electrical power generation using the alternating magnetic field energy of a SQUID.     

Entanglement of Two Superconducting Charge Qubits Induced by Quantized Radiation Field

We consider two superconducting charge qubits coupled by a single-mode quantized field. We suppose that the two superconducting charge qubits be initially prepared in the mixed and separable state. As time evolves, we will investigate the entanglement between two superconducting charge qubits induced by the quantized field.