Vapor-Cell-Based Atomic Electrometry for Detection Frequencies below 1 kHz

Rydberg-assisted atomic electrometry using alkali-metal atoms contained inside a vacuum environment for detecting external electric fields at frequencies below a few kilohertz has been quite challenging due to the low-frequency electric-field-screening effect that is caused by the alkali-metal atoms adsorbed on the inner surface of the container. We report a very slow electric-field-screening phenomenon with a time scale up to the order of seconds on a rubidium-vapor cell that is made of monocrystalline sapphire. Using this sapphire rubidium-vapor cell with an optically induced, internal bias electric field, we demonstrate vapor-cell-based, low-frequency atomic electrometry that responds to the electric field strength linearly. Limited by the given experimental conditions, this demonstrated atomic electrometer uses an active volume of $11\phantom{\rule{0.2em}{0ex}}{\mathrm{mm}}^{3}$ and delivers a spectral noise floor of around $0.34\phantom{\rule{0.2em}{0ex}}\mathrm{mV}/\mathrm{m}\phantom{\rule{0.1em}{0ex}}\sqrt{\mathrm{Hz}}$ and a 3-dB low cutoff frequency of around 770 Hz inside the vapor cell. This work investigates a regime of vapor-cell-based atomic electrometry that was seldom studied before, which may enable more applications that use atomic electric-field-sensing technology.