Metrology of RF electromagnetic fields using trap loss spectroscopy in cold Rydberg atoms

Due to their high sensitivity, wide frequency range, SI-traceability and reduced size at low frequency, Rydberg atoms based- sensors of RF/THz fields hold great prospects for many applications including telecommunications, radar, and THz imaging. So far, almost all of these sensors have consisted in probing by means of EIT spectroscopy the Autler-Townes effect resulting from the interaction between the field and a warm vapor of alkaline Rydberg atoms. Despite significant improvement using heterodyning, this approach suffers several limitations caused by broadening mechanisms inherent to warm vapors, and by using EIT as a probe. We report here on a new approach based on trap-loss spectroscopy of the Autler-Townes effect in cold 87Rb atoms confined in a MOT. The doublet of dressed Rydberg states measured this way obeys well the theoretical model of Autler-Townes effect provided lightshifts from neighboring Rydberg states are considered, suggesting the possibility to infer the characteristics of the field from those of the doublet. Study of the resulting sensor revealed a very good linearity, with residual errors of 1%, and a resolution of 5 µV/cm after an integration time of 2600s.