Three-Photon Laser Excitation of Single Rydberg Rubidium Atoms in an Optical Dipole Trap

Three-photon laser excitation of single rubidium atoms in an optical dipole trap (ODT) into the ³⁷P Rydberg state by laser radiation with wavelengths of 780, 1367, and 743 nm has been experimentally demonstrated. The excitation to Rydberg states is detected by an optical method using the losses of atoms in the ODT. The laser excitation spectra of single Rydberg atoms in the ODT are recorded, and the dependence of the excitation probability on the laser pulse duration is measured. The measured spectrum width was 2 MHz. Experiments on fluorescence quenching spectroscopy of a cloud of cold atoms in a magneto-optical trap during the three-photon laser excitation of atoms to Rydberg states are also carried out. The experimental results are compared with a numerical calculation. Methods for increasing the accuracy of the coherent three-photon laser excitation of Rydberg atoms in the ODT are considered.