Self-Calibrating broadband electrometer for radio frequency and microwave fields detection utilizing non-resonant, non-linear electric field-mixing in Rydberg atoms

We have developed a self-calibrating electromagnetic field sensor for measuring the spectral amplitude of broad-band or multi-frequency RF and microwave fields. This sensor utilizes Rydberg Rubidium atoms in a room temperature vapor cell, and electromagnetically induced transparency (EIT) laser spectroscopy as an optical readout. Unlike other schemes that rely on resonant coupling between Rydberg states [1], our electrometer is based on non-resonant dressing of the Rydberg atoms by the combination of an RF/microwave signal field and a DC, low frequency (LF), or RF reference field, exploiting the extraordinarily large electric field sensitivity of Rydberg atoms. In the combined signal and reference fields, the Rydberg excitation spectrum measured through laser spectroscopy exhibits a primary resonance feature shifted from the zero-field resonance position, and flanked by subsidiary resonances, or sidebands. Measurement of the shift of the primary Rydberg resonance, along with the ratio of the sideband to primary Rydberg resonance amplitudes, enables the determination of the spectral amplitude of the signal field, with high sensitivity across a broad spectral range that is not limited by a resonant, or near resonant, atomic response.

This work has been funded by National Science Foundation and the University of Virginia.

[1] J. A. Sedlacek et al., Nat. Phys. 8, 819 (2012).