Superconducting magnetic field sensing apparatus having digital output,

Abstract

A magnetometer having high sensitivity and high resolution is achieved using superconductive circuit elements. The magnetometer includes a pick-up coil, amplifying transformer quantum flux parametron (QFP), latch, feedback gate and feedback inductor fabricated with superconducting elements and coupled to a bidirectional counter. The magnetometer implements an on-chip negative feedback loop. The pick-up coil senses an external magnetic field or gradient resulting in an induced current which is amplified and fed to the QFP which generates a directional indicator signal sent to the latch. When the polarity of the indicator is indicated as corresponding to the polarity of a latch clock signal, a current signal is sent to the feedback gate causing a packet of quantum flux to be generated. The packet is fed back through the feedback inductor, inducing a current in the pick-up coil which opposes the induced current attributable to the external magnetic field. When the induced current in the pick-up coil attributable to the external magnetic field is offset by the induced current attributable to the feedback flux, the magnetometer stabilizes.