Efficient Formation of Ultracold Molecules with Chirped Nanosecond Pulses

TL;DR

This paper demonstrates efficient ultracold molecule formation using frequency-chirped nanosecond pulses, combining experiments and quantum simulations to optimize coherent processes for improved production rates.

Contribution

It introduces a method for ultracold molecule formation with chirped pulses, showing how pulse shaping enhances efficiency and aligning experimental results with simulations.

Findings

Coherent formation dominates with proper chirp parameters.

Positive chirp produces molecules via photoassociation and stimulated emission.

Chirp shaping significantly increases formation rate.

Abstract

We describe experiments and associated quantum simulations involving the production of ultracold $^{87}$Rb$_{2}$ molecules with nanosecond pulses of frequency-chirped light. With appropriate chirp parameters, the formation is dominated by coherent processes. For a positive chirp, excited molecules are produced by photoassociation early in the chirp, then transferred into high vibrational levels of the lowest triplet state by stimulated emission later in the chirp. Generally good agreement is seen between the data and the simulations. Shaping of the chirp can lead to a significant enhancement of the formation rate. Further improvements using higher intensities and different intermediate states are predicted.