Driving Alkali Rydberg Transitions with a Phase-Modulated Optical Lattice

We develop and demonstrate a spectroscopic method for Rydberg-Rydberg transitions using a phase -controlled and-modulated, standing-wave laser field focused on a cloud of cold 85Rb Rydberg atoms. The method is based on the ponderomotive (A(2)) interaction of the Rydberg electron, which has less-restrictive selection rules than electric-dipole couplings, allowing us to probe both nS(1/2)? nP(1/2) and nS(1/2)? (n + 1)S-1/2 transitions in first order. Without increase in laser power, third-and fourth-order subharmonic drives are employed to access Rydberg transitions in the 40 to 70 GHz frequency range using widely available optical phase modulators in the Ku band (12 to 18 GHz). Measurements agree well with simulations based on the model we develop. The spectra have prominent Doppler-free components with linewidths ?200 kHz. The method paves the way for optical Doppler-free high-precision spectroscopy of Rydberg-Rydberg transitions and for spatially selective qubit manipulation with pm-scale resolution in Rydberg-based simulators and quantum computers, provided that magic states are chosen and that the atoms are sufficiently cold.

Automated summary

This study develops and demonstrates a spectroscopic method for Rydberg-Rydberg transitions using a phase-controlled laser field. The method enables the detection of Rydberg transitions with less-restrictive selection rules and provides Doppler-free spectra with narrow linewidths. This new method opens up possibilities for high-precision spectroscopy and qubit manipulation in Rydberg-based systems.