DETECTING ONE OR MORE PHOTONS FROM THEIR INTERACTIONS WITH PROBE PHOTONS IN A MATTER SYSTEM

摘要

A device capable of efficiently detecting a single-photon signal includes a matter system (112), sources (114 and 610) of a first beam and a second beam, and a measurement (420) system. The matter system (112) has a first energy level and a second energy level such that a signal photon couples to a transition between the first energy level and the second energy level. The first beam contains photons that couple to a transition between the second energy level and a third energy level of the matter system (112), and the second beam contains photons that couple to a transition between the third energy level and a fourth energy level of the matter system (112). The measurement system (420) measures a change in the first or second beam to detect the absence, the presence, or the number of the photons in the signal.