HTS SFQ logic circuit built with YBCO grain boundary junctions

Abstract

We have designed, fabricated, and operated an SFQ RS flip-flop based on YBCO grain boundary junctions formed on a SrTiO3 bi-crystal substrate. The circuit consisted of a read SQUID and an RS flip-flop, which were magnetically coupled together. The circuit operated correctly in the temperature range of 65-71 K. Especially, at 71 K, this circuit operated correctly over the 100 reset-set operations without making errors. We also measured the effect of noise on switching a Josephson junction to the voltage state in an SFQ circuit. (C) 1999 Elsevier Science Ltd. All rights reserved.