RF-amplifier-free Superconducting Nanowire Single-Photon Detector System

We used a superconducting nanowire single photon detector integrated with a current reservoir in a closed-cycle cryocooler to demonstrate RF-amplifier-free photon counting. By removing the RF amplifiers, we completely eliminated the capacitor-coupling effect, consequently increased the switching current from 48.5 μA to 50.5 μA and increased the device efficiency from 26% to 32%. The L/R time constant was reduced by a factor of 1.27.