Waveform measurement of a low-frequency electric fields with a Rydberg atom-based sensors

Abstract

The high polarizabilities of Rydberg atoms enable multi-dimensional parameter measurements of electromagnetic fields. In this paper we report an atomic antenna by employing Rydberg atoms in room-temperature cesium vapor cell. We employ the cascade-type two-photon excitation electromagnetically induced transparency (EIT) spectroscopy to measure the Rydberg energy levels. EIT is a destructive interference effect with a narrow linewidth, and it can be used to detect a small electric field by Autler-Townes splitting or Stark shifts.<br>In experiments, a low-frequency electric field with ~kHz frequency is introduced by using built-in electrode technique in the room-temperature atomic gas cell. The interaction between Rydberg atom and electric field induces the Stark shifts, where the electric field amplitude is converted into the corresponding two-photon detuning by EIT effect. Furthermore, the low-frequency electric field amplitude is converted into the corresponding intensity signal of probe beam in EIT spectroscopy, that allow to measure the electric field frequencies. Under weak electric field conditions, there is an approximate linear relationship between EIT transmission signal and input electric field amplitude, which enables to detect waveform, amplitude, and frequency parameter. We have demonstrated an atomic antenna with optical probing method. The EIT effect allows increasing the response bandwidth from ~MHz to hundreds of MHz with increasing the probe beam and coupling beam power. Under this condition, the EIT spectroscopy can extend a measure bandwidth to ~MHz, that will provide a scalable approach for high-frequency electric fields.