Letter: A stable frequency standard based on the one-color two-photon 5S-7S transition of rubidium at 760 nm

摘要

We report an experimental investigation of the 5S_(1/2)-7S_(1/2) one-color two-photon transition in rubidium vapor with a single continuous-wave laser operating at 760 nm. By utilizing a robust intensity modulation method, high-resolution spectra with a signal-to-noise ratio of ～120 are obtained. A perfect match between experimental results and the theoretical analysis is obtained by characterizing the probability of a two-photon transition with vapor temperature and laser power. Moreover, the influence of electric dipole selection rules on the two-photon transition is also investigated by changing the polarization of the laser beam. Since the 5S_(1/2)-7S_(1/2) two-photon transition is insensitive to stray magnetic fields and has an extremely narrow linewidth, we confidently believe that it can provide a concrete frequency standard for quantum telecommunication in the S-band window (1480-1530nm). Meanwhile, the atomic system at 760 nm will serve as a good candidate for a quantum repeater.