8-channel array of single-chip SQUIDs connection to Josephson multiplexer

A single-chip superconducting quantum interference device (SQUID) array interfaced to a Josephson multiplexer has been developed. A single-chip SQUID consists of a SQUID sensor and a superconducting feedback circuit. Its output is digital and can be processed with a Josephson digital circuit. The parallel output signal from the SQUID array was time-division multiplexed and summed at a single output cable by a Josephson multiplexer in a cryogenic environment. This method reduces the number of cables required for connection between the SQUID chips and room-temperature electronics. The eight-channel SQUID was tested with a 160-gate Josephson multiplexer. The authors verified the operation of the SQUID array at bias frequencies up to 5 MHz, while the multiplexer was operated at 120 MHz. The measured sensitivity was 1.13*10/sup -5/ Phi /sub 0//(Hz)/sup 1/2/ and the cut-off frequency was 350 Hz.<
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