高温超電導量子干渉素子の量子的特性を考慮した数値解析に関する研究

超電導

A superconducting quantum interference device (SQUID) is a high sensitive magnetic sensor. It can measure a very small amount of magnetic flux, and is widely used in various applications such as a nondestructive evaluation (NDE) and a low field magnetic resonance imaging (MRI). In many cases of such applications, the SQUID is used inside a magnetic shielding room. The reason is that the SQUID transitions to unstable state under magnetic noise. Recently, to improve the robustness with respect to magnetic noise of the SQUID sensor and to realize the stable operation in normal magnetic environment, many researches are widely performed. In this study, the numerical simulation of SQUID is performed by the finite element method (FEM). From the simulation, the effectiveness of the superconducting film magnetic-shield which has been proposed to improve the performance of the SQUID magnetometer is confirmed. Moreover, the analysis taking into account the characteristic of the Josephson junction is performed to express the phenomenon of the SQUID more precisely. To consider the quantum behavior of Josephson junction in the SQUID, the equivalent circuit is embedded in FEM. As a result, the macro-scale simulation taking account of the micro-scale phenomenon is performed.