Sensitivity improvement of Rydberg atom-based microwave sensing via electromagnetically induced transparency

Abstract

A highly excited Rydberg atom via electromagnetically induced transparency with two color cascading lasers has extreme sensitivity to electric fields of microwave ranging from 100 MHz to over 1 THz. It can be used as susceptible atom-based microwave communication antennas where the carrier wave usually works exactly resonant to the transition between a pair of adjacent Rydberg states with large electric dipole moment. A technique of superheterodyne with a strong on-resonant local microwave oscillator is employed to induce considerable Autler-Townes splitting where the antennas has a highest dynamic response to another weak target signal microwave carrier. To further improve the sensitivity of atomic antenna in communication, we detune the carrier microwave frequency off resonance forming an asymmetrically optical splitting and fix the coupling laser frequency at the shoulder of the stronger one, and optimize the local field strength simultaneously. It gives a sensitivity of 12.50(04) nVcm −1 • Hz −1/2 . Its enhancement mechanism of sensitivity is also proved by a theoretical simulation.

Bright and dark Autler-Townes states in the atomic Rydberg multilevel spectroscopy

“…In the AT experiments conducted in Refs. [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23] the detection of Rydberg atoms by electromagnetically induced transparency (EIT) optical spectroscopy or selective electric field ionisation allows the experimentalists to probe the frequency and amplitude of the mw driving radiation. The mw field amplitude is derived from the AT modification of the Rydberg excitation.…”

“…When one transition is driven by a intense laser, the second transition spectrum is composed by a resonant doublet with the separation between the two components determined by the laser electric field. This process, well characterised in atomic/molecular and solid state spectroscopy, has received recently a new interest within a different context: the precise determination of a microwave (mw) field amplitude for calibration purposes as in [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. The mw radiation is applied to cold atoms in Rydberg states where the electric dipole moment is very large, such that even a weak mw field produces AT splitting.…”