Digital superconducting quantum interference device having an extended dynamic range

摘要

A superconducting quantum interference magnetometer comprises a superconducting pickup coil (111) for interlinking with an unknown magnetic flux and causing to flow an induction current, a superconducting detector (119) of a superconducting quantum interference device coupled magnetically with the superconducting pickup coil for producing output voltage pulses in response to the unknown magnetic flux, a superconducting feedback circuit (118) connected to the superconducting detector for receiving the output voltage pulses therefrom and feeding back a feedback magnetic flux to the superconducting pickup coil in response to each output voltage pulse such that the feedback magnetic flux counteracts the unknown magnetic flux, a resistance fixture (115) provided in the vicinity of the superconducting pickup coil for causing a transition in a part of the superconducting pickup coil a transition from a superconduction state to a normal conduction state in response to the drive current, and a controller (116) connected to the resistance fixture and the superconducting detector for receiving the output pulses therefrom and producing a drive current for energizing the resistance fixture. Simultaneously to the energization of the resistance fixture, the controller resets the feedback circuit such that the counteracting feedback magnetic flux is deenergized.