Stochastic Kinetics Of A DC SQUID System Driven By Thermal Noises

The advent of high-Tc superconductors gave great impetus to the development of thin-film superconducting quantum interference devices (SQUIDs) for operation at temperatures up to the boiling point of liquid nitrogen, 77K. With the development of operation temperature, intrinsic noise of the device has a much stronger effect on its performance. Researching the de SQUID theoretically is based on equivalent circuit method (such as RCS.J , RS.J model) for analyzing its physical performance.In this thesis, we will retrospect the research evolvement of dc SQUID theoretically and experimentally, and introduce the research springboard, methods and significance. In Chapter 2, it will be introduced that how to solve the Fokker-Planck equation corresponding to the Langevin equations which depict, the kinetics of dc SQUID. How to solve the Fokker-Planck equation depicting the kinetics of dc SQUID with a resistively shunted resistance will be introduced in Chapter 3. The effect of the shunted resistance is researched using the method of expanding a small parameter and the results are well agreed with the numerical simulations.Numerical simulation is a basic method to research dc SQUID. In Chapter 4, we put forward a simple method to simulate dc SQUIDs1 characteristics by separate two freedoms into four. It is also investigated by numerical simulations in the case of asymmetry and shunted with resistance.DC RSQUIDs are used a.s very sensitive voltage-to-frequency converts in the femto- and picovolt range. There are few papers for researching it theoretically. In Chapter 5, effects of many parameters on the output voltage signalare investigated numerically.