Adsorbate dynamics on a silica-coated gold surface measured by Rydberg Stark spectroscopy

TL;DR

This study measures and analyzes electric fields caused by rubidium atoms on a silica-coated gold surface, demonstrating methods to reduce stray fields and improve conditions for trapping Rydberg atoms near surfaces.

Contribution

It provides the first detailed measurement of adsorbate-induced electric fields on a silica-coated gold surface and shows how to mitigate these fields for quantum experiments.

Findings

Electric field measured is higher than on pure metal but consistent with silica surfaces.

UV light and mild heating can reduce the electric field in a single cycle.

Field buildup occurs over thousands of cycles, but can be rapidly decreased.

Abstract

Trapping a Rydberg atom close to a surface is an important step towards the realisation of many proposals of quantum information or hybrid quantum systems. One of the challenges in these experiments is to overcome the electric field emanating from contaminations on the surface. Here we report on measurements of an electric field created by $^{87}$Rb atoms absorbed on a 25$\,$nm thick layer of SiO$_2$, covering a 90$\,$nm layer of Au. The electric field is measured using a two-photon transition to the 23$D_{5/2}$ and 25$S_{1/2}$ state. The electric field value that we measure is higher than typical values measured above metal surfaces, but is consistent with other measurements above SiO$_2$ surfaces. In addition, we measure the temporal behaviour of the field and observe that we can reduce it in a single experimental cycle, using UV light or by mildly heating the surface, whereas the buildup of the field takes thousands of cycles. We explain these results by a change in the ad-atoms distribution on the surface. These results indicate that the stray electric field can be reduced, opening new possibilities for experiments with trapped Rydberg atoms near surfaces.