Development of RF Sensor Based on Two-Cell Squid

摘要

The RF directional sensor based on phase-sensitive detection using two sorts of Josephson parametric amplifiers has been analyzed and investigated experimentally. To construct the Josephson parametric amplifier, we use a SQUID (either single-cell SQUID or two-cell SQUID) embedded in a superconducting coplanar waveguide. We operated the circuit at a frequency of several GHz and measured the amplitude response of the SQUID-based Josephson parametric amplifier. Nonlinearity and flux tunability in the reported experiments was limited by relatively large critical current density and therefore small nonlinear inductance of the SQUID. The demonstrated phase sensitivity was 1.2 dB / rad. It appears feasible to improve the sensitivity of developed RF sensor by reducing the critical current of the Josephson junctions.