Josephson threshold detector in the phase diffusion regime

We demonstrate that the performance of threshold detectors based on Al Josephson junctions can be significantly improved by exploiting the phase diffusion regime. When the escape dynamics of the detector switches to this regime, a decrease in both - dark count rate and the standard deviation of switching current is simultaneously observed. However, this effect is essential for (i) critical currents below 100 nA, and (ii) temperatures of the order of several hundreds millikelvin. Importantly that for such detectors optimal performance occurs at finite temperatures, making the microwave single photon detection feasible even in the sub-K range. Possible explanation of these findings is discussed.