Metrology of electromagnetic fields with cold Rydberg Atoms

Rydberg atoms have large dipole moments, making them good candidates for sensitive measurements of electromagnetic fields [1]. Compared to classical antennae, their size is independent of the wavelength to be measured, and they are broadly tunable, from MHz to THz typically. While most of intense research effort worldwide have focused on room-temperature vapors so far, using cold atoms (nowadays compatible with field applications [3]) has the advantage of strongly reducing the frequency broadening associated with Doppler effect, while increasing the interaction time between the atoms and the probing beams. We have recently developed at ONERA a novel approach to sense electromagnetic fields with cold 87 Rubidium Rydberg atoms based on trap-loss spectroscopy in a magneto-optical-trap (MOT). This technique stands out for its simplicity, relying solely on fluorescence measurements and shows a linear response at the percent level, a resolution on the order of 5 μV/cm and the possibility to measure both the MW amplitude and frequency at the same time [2].

We will present at the conference our latest results in microwave sensing with cold Rydberg atoms: we performed a comprehensive study of noise sources that impact the trap-loss spectroscopy method, that lead us to implement several improvements to our laser system's linewidth and stability, yielding an improvement in the sensor sensitivity and stability by more than one order of magnitude We will discuss our mid-term objective of trapping and manipulating cold atoms in optical tweezers to study diverse operational regimes: atom-ensemble configurations, enhancement of spatial or frequency resolution and harnessing atom-atom interactions to create metrologically useful quantum states.

[1] Fancher, C. et al (2021). Rydberg atom electric field sensors for communications and sensing. IEEE Transactions on Quantum Engineering, 2, 1-13.

[2] Duverger, R. et al (2024). Metrology of microwave fields based on trap-loss spectroscopy with cold Rydberg atoms. Physical Review Applied, 22(4), 044039.

[3] Bidel, Y. et al (2018). Absolute marine gravimetry with matter-wave interferometry. Nature communications, 9(1), 627.