A continuous-wave maser operating on a two-photon transition between Rydberg levels is expected to oscillate with about one atom and a few tens of microwave photons at any time in its superconducting cavity. We analyze in detail the characteristics of this new microscopic quantum electronics device presently under construction in our laboratory.

• Received 31 July 1986

DOI:https://doi.org/10.1103/PhysRevA.35.154