Origins of Rydberg-Atom Electrometer Transient Response and Its Impact on Radio-Frequency Pulse Sensing
Stephanie M. Bohaichuk, Donald Booth, Kent Nickerson, Harry Tai, James P. Shaffer
Abstract
Rydberg atoms show significant promise as the basis for highly sensitive detectors of continuous radio-frequency (rf) electric fields (E fields). Here, we study their time-dependent response to pulse-modulated rf E fields at 19.4 GHz using a cesium vapor cell at room temperature. We use density-matrix simulations to explain the timescales that shape the transient atomic response under different laser conditions, finding them to be limited by dephasing mechanisms, including transit-time broadening, Rydberg-Rydberg collisions, and ionization. Using a matched filter, we demonstrate the detection of individual pulses with durations from 10 \textmu{}s down to 50 ns and amplitudes from 15 000 \textmu{}V ${\mathrm{cm}}^{\ensuremath{-}1}$ down to about 170 \textmu{}V ${\mathrm{cm}}^{\ensuremath{-}1}$, corresponding to a sensitivity of about 240 nV ${\mathrm{cm}}^{\ensuremath{-}1}$ ${\mathrm{Hz}}^{\ensuremath{-}1/2}$. Finally, we highlight the potential of a Rydberg vapor cell as a receiver by detecting pulse trains from a rotating emitter on a simulated passing aircraft.