Doppler sensitivity and optimization of Rydberg antennas*

Radio frequency antennas based on Rydberg atoms should in principle be able to achieve sensitivities beyond those of any conventional wire antenna, especially at lower frequencies where very long wires are needed to accommodate the growing wavelength. Given their low electromagnetic profile, they have already demonstrated improvement over conventional wire antennas as calibration standards for electric field measurements. This paper presents a detailed theoretical investigation of Rydberg antenna sensitivity, elucidating parameter regimes that could cumulatively lead to 2--3 orders of magnitude sensitivity increase over currently explored setups. Of special interest are three-laser setups proposed to compensate for atom motion-induced Doppler spreading. Such setups are in indeed shown to be advantageous, but only because they restore sensitivity to expected Doppler-limited value, removing significant additional off-resonance reductions.