High-angular-momentum Rydberg states in a room-temperature vapor cell for dc electric-field sensing

Abstract

We prepare and analyze Rydberg states with orbital quantum numbers ℓ≤6 using three-optical-photon electromagnetically induced transparency (EIT) and radio frequency (rf) dressing, and employ the high-ℓ states in electric-field sensing. Rubidium-85 atoms in a room-temperature vapor cell are first promoted into the 25F5/2 state via Rydberg-EIT with three infrared laser beams. Two rf dressing fields then (near-)resonantly couple the 25F, 25H(ℓ=5), and 25I(ℓ=6) Rydberg states. The dependence of the rf-dressed Rydberg-state level structure on rf powers, rf and laser frequencies is characterized using EIT. Furthermore, we discuss the principles of dc-electric-field sensing using high-ℓ Rydberg states and experimentally demonstrate the method using test electric fields of ≲50 V/m induced via photo-illumination of the vapor-cell wall. We measure the highly nonlinear dependence of the dc-electric-field strength on the power of the photo-illumination laser. Numerical calculations, which reproduce our experimental observations well, elucidate the underlying physics. Our paper is relevant to high-precision spectroscopy of high-ℓ Rydberg states, Rydberg-atom-based electric-field sensing, and plasma electric-field diagnostics.