Experimental determination of optimum operating conditions of a superconducting interferometer

Abstract

A superconducting interferometer (SQUID) behaves as a nonlinear impedance, the value of which changes periodically when an linearly increasing flux is applied to it. Conditions of utilization of this device, when stimulated by an rf flux to obtain maximum sensitivity, where studied and were found to satisfy the relation k2Q≃1 and 2πLsic/φ0≃1. Experimental results show that the signal response increases as √f and the sensitivity obtained at 245 MHz is 4 × 10−5 φ0 Hz−1/2.