In studying Rydberg atoms we must take specially care with stray electric fields E, that can escalate to a severe control when the goal is to study the behavior of the interaction due to the static electric field applied. For this during my Phd project we have built a set of 8 independent electrodes were each can be controlled by applying an independent electric potential.
This give us a 3-dimensional freedom, in a way that even quadrupole electric fields are possible to be generated. This geometry was chosen in way that could give us a good optical access to the atomic sample.
At the middle of the Ultra-High-Vacuum chamber we can cool and trap an atomic sample of rubidium 85 using standard magneto-optical techniques. A QUEST (Quasi Static Trap) optical trap created by a high power focused CO2 laser with wavelength of 10.6 microns is loaded from the MOT (Magneto Optical Trap). The electric field can be independent measure by use of Förster resonances using the resonant energy transfer process,whilst the electric field is scanned, it drives resonant energy population transfer from 37D to 39P by several peaks due to the Stark energy splitting.
Throughout several iterations the electric field can be calibrated in every orthogonal direction Ex, Ey and Ez. This control is a clear improvement to the experimental setup, in the old system a pair of parallel plates with 95% transparency was used to apply electric field in only one direction Ez. In this case was not possible to cancel stray electric field in Ex and Ey directions.
More details about this experimental setup and electrodes development, testing, calibration, etc, can be found on my Phd, thesis here.