A new pixellated device that could detect not only the position of an arriving photon, but also its energy, has been proposed by Peter Day and Henry LeDuc of the Jet Propulsion Laboratory, together with Jona Zmuidzinas and colleagues at Caltech.
The device exploits the change in kinetic inductance of a small superconductor when some of its Cooper pairs are broken up by an incident photon. The higher the energy of the photons, the more pairs are broken up, and the more slowly a current can respond to outside changes. This effective inductance can be measured with microwave techniques.
While there remains much to be done to make this into a practical imaging device, it could revolutionize astronomy, in particular the measurements of the cosmic microwave background radiation, and lead to many other interesting new applications.
Further reading
Peter K Day et al. 2003 Nature 425 817.