Effect of dipole interactions on the properties of an expanding ultracold plasma: A study using quantum mechanical scattering theory

TL;DR

This paper investigates how dipole interactions influence the behavior of expanding ultracold plasmas, using quantum mechanical scattering theory to explain experimental anomalies and extend understanding across different atomic species.

Contribution

It extends a quantum treatment to analyze dipole interactions in ultracold plasmas for various atoms, explaining observed phenomena and plasma expansion dynamics.

Findings

Quantum interactions cause faster plasma expansion.

Extended model explains previously anomalous experimental results.

Dipole interactions significantly affect ultracold plasma properties.

Abstract

While generating ultracold plasma (UCP) by photoinization of laser-cooled atoms, only a small fraction of atoms are ionized, and the remaining neutrals interact with the electrons present therein. These interactions, in addition to the Coulomb interactions between ions and electrons, cause phenomena such as ionization of Rydberg atoms and three body recombination, all of which affect the overall behaviour of the ultracold plasma. We had earlier developed a quantum treatment to analyze these interactions and investigated the ionization of Rydberg atoms in Cesium, which showed good agreement with measured results. We now extend it to other atomic species to investigate Rydberg ionization, and other effects such as three-body recombination and a resulting additional `quantum pressure' which causes a faster expansion of the UCP. Our results successfully explain experimental observations which were hitherto deemed as `anomalies'.