Fast Penning Ionization of Cold Rydberg atoms in an Electric Field

TL;DR

This study demonstrates that a static electric field significantly accelerates Penning ionization in cold Rydberg atoms by lowering the ionization threshold and enhancing dipole interactions, which could impact quantum system stability and control.

Contribution

It provides experimental evidence and a theoretical model showing electric fields dramatically increase Penning ionization rates in cold Rydberg gases, revealing new ionization channels.

Findings

Ionization rates are orders of magnitude higher with electric field.

Electric field lowers the Rydberg ionization threshold.

Dipole interactions lead to double ionization channels.

Abstract

We observe a fast Penning ionization in a dilute gas of cold rubidium Rydberg atoms, in the presence of a static electric field of 50 V/cm, with the ionization rate coefficients for two specific states being measured, which are orders of magnitude higher than the theoretical predictions in field-free space. Our analysis based on a polarized two-atom model reveals that the ionization threshold of Rydberg atoms is lowered by the static electric field, reducing the energy exchange required for Penning ionization and increasing the ionization rate. Beyond this, the dipole-dipole interaction strengthened by the electric field between two Rydberg atoms at a micrometer-scale distance leads to double ionization of the atoms pair, opening a new autoionization channel. Such enhancement of the Penning ionization by a static electric field poses both a threat to the stability and a potential control strategy for quantum systems composed of cold Rydberg atoms with micrometer-scale interatomic separations.