Proposal for a Beat Oscillating Superconducting Quantum Interference Device

概要

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We describe a new dc-superconducting quantum interference device (SQUID) circuit of the FM type, which has a large coefficient for converting an applied magnetic flux into a frequency of MHz band or a lower band. The circuit consists of a SQUID amplifier composed of two stages, formed by a superconducting weak link and two dc-SQUID elements with nonhysteretic characteristics. In the first stage, the weak link and dc-SQUID elements are connected in parallel and operated by a common bias voltage. Since the respective elements oscillate with high frequencies by the ac Josephson effect, the two frequencies interact with each other, so that, the first stage generates a beat signal of a lower frequency. In the second stage, the other dc-SQUID element with a intrinsic flux gain enhances the beat signal generated during the first stage. A theoretical analysis of the circuit with computer simulation shows that the beat frequency is a periodical function of the magnetic flux, and the SQUID amplifier with two stages can improve the flux sensitivity.
Publication Office, Japanese Journal of Applied Physics, Faculty of Science, University of Tokyoの論文
1998-05-15