Dephasing of ultracold cesium $80D_{5/2}$-Rydberg Electromagnetically Induced Transparency

TL;DR

This paper investigates how strong dipole-dipole interactions in ultracold cesium Rydberg atoms cause dephasing and metastability in electromagnetically induced transparency, revealing nonlinear optical effects and state transfer dynamics.

Contribution

It provides experimental insights into dephasing mechanisms and metastability in Rydberg EIT involving the 80D5/2 state under strong interactions.

Findings

Dephasing rate increases nonlinearly with incident photon number.

Optical depth grows linearly with time before saturation.

State transfer times are comparable to EIT decay times.

Abstract

We study Rydberg electromagnetically induced transparency (EIT) of a cascade three-level atom involving 80$D_{5/2}$ state in a strong interaction regime employing a cesium ultracold cloud. In our experiment, a strong coupling laser couples 6$P_{3/2}$ to 80$D_{5/2}$ transition, while a weak probe, driving 6$S_{1/2}$ to 6$P_{3/2}$ transition, probes the coupling induced EIT signal. At the two-photon resonance, we observe that the EIT transmission decreases slowly with time, which is a signature of interaction induced metastability. The dephasing rate $\gamma_{\rm OD}$ is extracted with optical depth OD = $\gamma_{\rm OD}t$. We find that the optical depth linearly increases with time at onset for a fixed probe incident photon number $R_{\rm in}$ before saturation. The dephasing rate shows a nonlinear dependence on $R_{\rm in}$. The dephasing mechanism is mainly attributed to the strong dipole-dipole interactions, which leads to state transfer from $nD_{5/2}$ to other Rydberg states. We demonstrate that the typical transfer time $\tau_{0(80D)}$ obtained by the state selective field ionization technique is comparable with the decay time of EIT transmission $\tau_{0({\rm EIT})}$. The presented experiment provides a useful tool for investigating the strong nonlinear optical effects and metastable state in Rydberg many-body systems.