Single superconducting quantum interference device multiplexer for arrays of low-temperature sensors

We present the design and experimental evaluation of a superconducting quan tum interference device (SQUID) multiplexer for an array of low-temperature sensors. Each sensor is inductively coupled to a superconducting summing l oop which, in turn, is inductively coupled to the readout SQUID. The flux-l ocked loop of the SQUID is used to null the current in the summing loop and thus cancel crosstalk. The sensors are biased with an alternating current, each with a separate frequency, and the individual sensor signals are sepa rated by lock-in detection at the SQUID output. We have fabricated a protot ype 8 channel multiplexer and discuss the application to a larger array. (C ) 2001 American Institute of Physics.