Josephson single infrared photon detector

Josephson junction (JJ) enables many high sensitivity detectors such as SQUID amplifier, magnetometer, microwave mixer, bolometer, and parametric amplifier. In the earliest realization of Josephson detectors during the 70’s, photodetection was one of the target applications before it fell out of competition due to the lack of good detection and coupling mechanism. However, new opportunities are now opening up for photodetection by exploiting the electrical and thermal properties of graphene in the superconducting-graphene-superconducting junctions. In this talk, we report the experimental detection of near-infrared (NIR) single photons by a graphene-based JJ via non-resonant Cooper-pair breaking and the resulting quasiparticle diffusion. Our method demonstrates an efficient mechanism for the electromagnetic wave to interact directly with the JJ. Such single photon detector is an enabling technology for quantum communication, quantum computing, and could be used as cryogenic optical interconnects.