Single-color two-photon spectroscopy of Rydberg states in electric fields

TL;DR

This study demonstrates the preparation and spectroscopic analysis of high-n Rydberg states in helium using two-photon excitation with polarized laser light, revealing their potential for trapping and deceleration in electric fields.

Contribution

It introduces a non-resonance-enhanced two-photon excitation method for creating high-n Rydberg states with specific quantum numbers in helium, suitable for advanced atomic manipulation.

Findings

Resolved individual Rydberg-Stark states in strong electric fields

Prepared long-lived high-|m_{ ext{ell}}| Rydberg states

Showed potential for Doppler-free excitation of positronium

Abstract

Rydberg states of atomic helium with principal quantum numbers ranging from n=20 to n=100 have been prepared by non-resonance-enhanced single-color two-photon excitation from the metastable 2 {^3}S{_1} state. Photoexcitation was carried out using linearly and circularly polarized pulsed laser radiation. In the case of excitation with circularly polarized radiation, Rydberg states with azimuthal quantum number |m_{\ell}|=2 were prepared in zero electric field, and in homogeneous electric fields oriented parallel to the propagation axis of the laser radiation. In sufficiently strong electric fields, individual Rydberg-Stark states were resolved spectroscopically, highlighting the suitability of non-resonance-enhanced multiphoton excitation schemes for the preparation of long-lived high-|m_{\ell}| hydrogenic Rydberg states for deceleration and trapping experiments. Applications of similar schemes for Doppler-free excitation of positronium atoms to Rydberg states are also discussed.