Motion-induced signal revival in pulsed Rydberg four-wave mixing beyond the frozen gas limit

TL;DR

This paper reports on pulsed four-wave mixing in a Rydberg atomic vapor, revealing a signal revival due to velocity class interference and confirming energy-momentum conservation through density dependence analysis.

Contribution

It demonstrates a novel observation of signal revival in Rydberg four-wave mixing beyond the frozen gas limit using pulsed excitation and phase-matched geometry.

Findings

Observation of a signal revival shortly after excitation pulse

Confirmation of energy and momentum conservation in the system

Density dependence analysis supports the underlying physical mechanisms

Abstract

We present measurements on pulsed four-wave mixing involving a Rydberg state in an atomic vapor cell. The excitation to the Rydberg state is conducted by a pulsed two-photon excitation on the nanosecond timescale that is combined with a third CW laser in phase-matched geometry yielding light emission on the same timescale. An additional signal peak is observed shortly after the pulse that can be attributed to a revival of constructive interference between different velocity classes of the radiating atomic dipoles. Furthermore we investigate the density dependence of the four-wave mixing signal. From the shape of the respective curve we are able to confirm energy and momentum conservation in the photonic part of the system.