Rabi resonances of a single molecule driven by rf and laser fields

Single molecules in a crystal at low temperature are driven simultaneously by a laser and by the electric field of an rf. At weak rf power, we observe Rabi transitions within doublets of dressed states, the first such observation in condensed matter in the optical domain. At higher rf power, resonances involving several rf photons appear. The interplay between rf and laser dynamics induces shifts and broadenings that are in excellent agreement with calculations from optical Bloch equations. We also directly display the Rabi and multi-rf-photon resonances by recording the fluorescence signal versus the rf frequency. [S0031-9007(98)07219-6].