Dynamics of Low-Density Ultracold Rydberg Gases

TL;DR

This study investigates the population dynamics of ultracold Rb Rydberg gases, revealing rapid state transfer likely due to superradiance and identifying black-body ionization as the main loss process.

Contribution

It introduces a combined detection method to analyze Rydberg state evolution and uncovers non-collisional mechanisms driving population transfer.

Findings

Rapid population transfer to other Rydberg states observed

Black-body ionization identified as dominant loss mechanism

Evidence suggests superradiant emission facilitates state transfer

Abstract

Population dynamics in weakly-excited clouds of ultracold $^{87}$Rb Rydberg atoms were studied by means of trap loss, fluorescence detection, and state dependent stimulated emission. Rydberg atoms were excited to various nl Rydberg states via continuous two-photon excitation from a magneto-optical trap. A stimulated emission probe laser was then used to bring the Rydberg atoms down to the 6P$_{3/2}$ state, allowing state-dependent detection of the Rydberg atoms. Measurements of trap loss and fluorescent emission reveal information about the evolution of the Rydberg populations. In particular, population in the initial Rydberg state quickly transfers to other Rydberg states by a non-collisional mechanism, likely superradiant emission. The trap-loss measurements are consistent with black-body ionization as the dominant loss mechanism.