A growing number of applications require the accurate detection of the elementary constituents of the radiation like single-photons or single-particles, the ultimate limit in detector sensitivity. The availability of high-performance detectors with such a sensitivity is crucial to continued progress in fundamental science like astrophysics as well as in the practical fields of quantum information processing, quantum communication, fluorescence analysis, chemical or biological luminescence analysis, single-molecule detection, and light detection and ranging (lidar).  Such quantum detectors re devices that convert incoming radiation (photons or particles) directly into an electrical signal, as opposed to thermal detectors that rely on the conversion of incoming radiation to heat.

Cryogenic quantum detectors exploit the low temperatures domain where performances are enhanced, environment noise is drastically reduced and, last but not least, new states of the matter with exciting properties, like superconductivity emerge. Superconductivity provides several attractive and efficient working principles for detector design.  The last three decades have seen a growing interest in the field of cryogenic quantum detectors which in the last decade has had a dramatic increase thanks to the progress in nanotechnologies which now allow to move from the micro to the nano scale of devices.

I will introduce the field and report the recent development in this exciting area of applied condensed matter.