Generation of non-classical states of light using highly excited atoms

Quality factor of up to 4×10¹⁰, corresponding to an average lifetime of a photon in the cavity of 0.3 s, are achieved. The photon lifetime is thus much longer than the interaction time of an atom with the maser field. The atoms used are rubidium Rydberg atoms pumped by laser excitation into the upper maser level, 63P₃2/, the lower maser level is either the 61D₅2/ or the 61D₃2/ depending on the cavity frequency. The atom field dynamics is observed by measuring the atoms in the upper or lower maser levels after the cavity. During the interaction the field in the cavity consists only of single or a few photons, nevertheless, it is possible to study the interaction in detail.