THz electrometry with Rydberg atoms and all IR lasers

Rydberg electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting in an atomic vapor cell can be used as novel methods for electric-magnetic field detection. Here we make use of 3 infrared lasers to realize a Rydberg EIT system in a thermal rubidium vapor cell. With the AT splitting induced by the THz radiation, we observe a linear trend between THz field amplitude and the frequency splitting of the absorption dips and EIT transmission peaks. Due to the well-known atomic transition dipole moment of the Rydberg state, the THz electric field can be calibrated from the frequency splitting, making this Rydberg atomic measurement system a practical tool for THz field detection.