WELL COUPLED dc SQUID WITH EXTREMELY LOW 1/F NOISE.

Abstract

A large number of extremely robust, thin film dc SQUIDs with excellent noise and coupling properties have been designed and fabricated. The lowest value of white noise observed corresponds to an energy factor of 350 H D-BAR . The low frequency (1/f) noise was reduced by careful operation of the device to less than 770 H D-BAR at 0. 1 Hz. This noise figure is an improvement of at least a factor of 60 over other devices with comperable coupling properties. The SQUID input coil inductance is 0. 7 mu H and the coupling efficiency alpha equals 0. 9.