Recently, the diverse properties of Rydberg atoms, which probably arise from its large electric dipole moment （EDM）, have been explored. In this paper, we report electric dipole moments along with Stark energies and charge densities of lithium Rydberg states in the presence of electric fields, calculated by matrix diagonalization. Huge electric dipole moments are discovered. In order to check the validity of the EDMs, we also use these electric dipole moments to calculate the Stark energies by numerical integration. The results agree with those calculated by matrix diagonalization.
The Stark structures in a cesium atom around n=18 are numerically calculated. The results show that the components of 20D states with a small azimuthal quantum number ｜m｜ shift upward a lot, and those with a large ｜m｜ shift downward a little within 1100 V/cm. All components of P states shift downward. Experimental work has been performed in ultracold atomic cesium. Atoms initially in 6P3/2 state are excited to high-n Rydberg states by a polarization light perpendicular to the field, and Stark spectra with ｜m｜=1/2,3/2,5/2 are simultaneously observed with a large linewidth for the first time. The observed spectra are analyzed in detail. The relative transition probability is calculated. The experimental results are in good agreement with our numerical computation.
We present a laser frequency locking to Rydberg transition with electromagnetically induced transparency（EIT）spectra in a room-temperature cesium vapor cell. Cesium levels 6S_（1/2）, 6P_（3/2）, and the n D_（5/2） state, compose a cascade three-level system, where a coupling laser drives Rydberg transition, and probe laser detects the EIT signal. The error signal, obtained by demodulating the EIT signal, is used to lock the coupling laser frequency to Rydberg transition. The laser frequency fluctuation, ~0.7 MHz, is obtained after locking on, with the minimum Allan variance to be 8.9 × 10^（-11）.This kind of locking method can be used to stabilize the laser frequency to the excited transition.
