Effect of Vapor-Cell Geometry on Rydberg-Atom-Based Measurements of Radio-Frequency Electric Fields

A new approach to detect absolute radio-frequency (rf) electric fields (E-fields) that uses Rydberg atoms at room temperature in vapor cells has been demonstrated recently. The large-transition dipole moments between energetically adjacent Rydberg states enable this technique to make traceable E-field measurements with high sensitivity over a large frequency range from 1 GHz to 1 THz. In this paper, we experimentally investigate how the vapor-cell geometry affects the accuracy of the measurements. We find that the effects of the vapor cell on the measured rf E-field are minimized by making the vapor-cell size small compared to the wavelength of the rf E-field.