DC characteristics of terahertz superconducting SIS mixers under alternating magnetic field

Terahertz Superconducting SIS (Superconductor-Insulator-Superconductor) mixers demonstrate ultra-high sensitivity close to the quantum limit. However, the DC characteristics of these mixes are vulnerable to interference, which may lead to decreased stability. In this study, the paper conducts a systematic experimental investigation into the impact of alternating magnetic field interference. It is observed that the DC bias voltage noise of superconducting SIS mixer under alternating magnetic field increases with the current derivative and is positively correlated with the coupling coefficient. Further experiments also reveal that measures such as increasing the distance between the bias source port and radiation source or reducing the area of the receiving circuit can decrease the coupling coefficient. The method can effectively suppress the interference caused by alternating magnetic field on DC characteristics of the terahertz superconducting SIS mixer.