Proximity SQUID Single-Photon Detector via Temperature-to-Voltage Conversion

We propose a single-photon detector based on a superconducting quantum interference device (SQUID) with superconductor-normal-metal-superconductor Josephson weak links. One of the two Josephson junctions is connected to an antenna, and is heated when a photon is absorbed. The increase of the weak-link temperature exponentially suppresses the Josephson critical current, thereby inducing an asymmetry in the SQUID. This generates a voltage pulse across the SQUID that can be measured with a threshold detector. Realized with realistic parameters, the device can be used as a single-photon detector - and as a calorimeter, since it is able to discriminate photon frequencies above 5THz with a signal-to-noise ratio larger than 20. The performance of the detector is robust with respect to working temperatures between 0.1 and 0.5K, and with respect to thermal noise perturbation.