Temperature-dependent bit-error rate of a clocked superconducting digital circuit

We measured the bit-error rate (BER) of an RS latch, a clocked SFQ circuit, A digital error-detection circuit was used to detect BER in the range unity to 10(-13); below 10(-7), the circuit was operated with a 12 GHz on-chip clock. BER was measured as a function of control current; both positive and negative control current was applied, lending to two distinct modes of error incidence. The error function curves extrapolate to 10(-80) for optimal control current at a temperature of 5.5 Ii, Measurements were repeated over the range 3-7K. Comparison to theoretical error-function estimates of BER indicate that the noise is strictly thermal.