Working with SQUIDs

摘要

The SQUID is a device based on the superconducting tun-nel junction. It is the most sensitive magnetic flux detector. In this article, we explain how a SQUID works and describe some applications where SQUIDs are essential. The fluctua-tion of the SQUID's critical current (1/f noise), the intrinsic noise limit of the sensor at low fre-quencies, is discussed. Research is being focused on lowering this noise to improve the performance of SQUIDs, as well as to allow Josephson junction based devices to be used for quantum computing. Another direction of research is to develop and implement time domain multiplexing schemes to allow very large numbers of SQUIDs to effective-ly run simultaneously. With multi-plexing, many new types of SQUID-based sensor arrays can be imple-mented.