Measurement of Grey Zone of a Josephson SFQ Memory Cell

Experimental studies of the grey zone of a single flux quantum memory cell using Josephson junctions are described. Probability of the meory cell operating in the grey zone and the dependence of the range of the grey zone on the cell critical current density are measured. From the results, the grey zone range that would produce an erroneous operation probability up to 10-16 is estimated. Results show that the margin of the bias current of the memory cell is 12%. This is 7% less than if the influence of the grey zone is ignored.