Technical Physics Letters
Quantum interference filters based on oxide superconductor junctions for microwave applications
A. V. Shadrin, K. Y. Constantinian, G. A. Ovsyannikov
Abstract
We have studied superconducting quantum interference filters (SQIFs) based on bicrystal neodymium gallate substrates, which can be used in the microwave frequency range. The characteristics of a serial SQIF have been compared for the first time with those of a single superconducting quantum interference device (SQUID) and a chain of serially connected SQUIDs with equal areas of superconducting loops. The regime of SQIF operation with a voltage-flux ( V -Φ) characteristic determined by the magnetic-field dependence of the critical current in the Josephson junction has been analyzed. It is shown that the output noise of a SQIF measured with a cooled amplifier in the 1–2 GHz range is determined by the slope of the V -Φ characteristic. The influence of a spread in the parameters of Josephson junctions in the SQIF on the integral V -Φ characteristic of the whole structure is considered.