Control of the effective value of the critical current of the RF SQUID by the high-frequency electromagnetic field

Abstract

An analysis of the influence of the high-frequency electromagnetic field on the amplitude-frequency and signal characteristics of RF SQUID and experimental verification are carried out. At low parameter βL, the RF SQUID behavior is well described analytically by the theoretical model. In experiment, basic operation scheme is used in which the interferometer is inductively connected to a resonant circuit driven by RF current at a frequency close to the resonance frequency of the circuit. It is shown that parameter βL, which distinguishes between hysteretic and nonhysteretic regimes, can be effectively adjusted to a desired value by applying the high-frequency field of a certain amplitude and frequency much higher than circuit resonance frequency. A significant increase in the conversion factor and sensitivity of the RF SQUID during this adjustment is discussed.