Multifunctional Superconducting Nanowire Quantum Sensors

Superconducting nanowire single-photon detectors (SNSPDs) offer high-quantum-efficiency and lowdark-count-rate single-photon detection. In a growing number of cases, large magnetic fields are being incorporated into quantum microscopes, nanophotonic devices, and sensors for nuclear and high-energy physics that rely on SNSPDs, but superconducting devices generally perform poorly in large magnetic fields. Here, we demonstrate robust performance of amorphous SNSPDs in magnetic fields of up to +/- 6 T with a negligible dark-count rate and unchanged quantum efficiency at typical bias currents. Critically, we also show that the SNSPD can be used as a magnetometer with a sensitivity of better than 100 mu T/root Hz and as a thermometer with a sensitivity of 20 mu K/root Hz at 1 K. Thus, a single-photon detector integrated into a quantum device can be used as a multifunctional quantum sensor capable of describing the temperature and magnetic field on chip simply by varying the bias current to change the operating modality from single-photon detection to thermometry or magnetometry.