Continuous-frequency weak electric field measurement with Rydberg atoms

Abstract

We demonstrate a continuous frequency electric field measurement based on the far off-resonant AC stark effect in a Rydberg atomic vapor cell. In this configuration, a strong far off-resonant field, denoted as a local oscillator (LO) field, acts as a gain shifting the Rydberg level to a high sensitivity region. An incident weak signal field with a few hundreds of kHz difference from the LO field is mixed with the LO field in Rydberg system to generate an intermediate frequency (IF) signal, which is read out by the Rydberg electromagnetically induced transparency (Rydberg-EIT) spectroscopy. Not like resonant EIT-AT spectra, we realize the electric field measurement of the signal frequency from 2 GHz to 5 GHz using a single Rydberg state. A minimum detectable filed strength is down to 2.31 µV/cm and a linear dynamic range is over 65 dB. The minimum detectable filed is comparable with a resonant microwave-dressed Rydberg heterodyne receiver using the same system, which is 1.45 µV/cm. We also show the system has an inherent polarization selectivity feature. Our method can provide a high sensitivity of electric field measurement and be extended to arbitrary frequency measurements.

Rydberg Atomic Sensor Sensitivity Optimization Using Detuned Microwave Field

“…Such results show that setting the appropriate frequency detuning can improve the system detection sensitivity, resulting in extra several dB sensitivity gain through this method when the device performance cannot be further improved. Considering the relationship between the local microwave electric field and the microwave signal in the heterodyne scheme, such results also mean that the heterodyne Rydberg atomic receiver can provide the same or better sensitivity as the resonance case in continuous weak microwave signal detection over a large frequency range [19]. The relaxation effect reduces the sensitivity of the system, which should be eliminated or reduced in experiments.…”