Very-high- and ultrahigh-frequency electric-field detection using high angular momentum Rydberg states

Abstract

We demonstrate resonant detection of rf electric fields from 240 to 900 MHz (very high frequency to ultrahigh frequency) using electromagnetically induced transparency to measure orbital angular momentum $L=3\ensuremath{\rightarrow}{L}^{\ensuremath{'}}=4$ Rydberg transitions. These Rydberg states are accessible with three-photon infrared optical excitation. By resonantly detecting rf in the electrically small regime, these states enable a new class of atomic receivers. We find good agreement between measured spectra and predictions of quantum defect theory for principal quantum numbers $n=45$ to 70. Using a superhetrodyne detection setup, we measure the noise floor at $n=50$ to be $13\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{V}/(\mathrm{m}\sqrt{\mathrm{Hz}})$. Additionally, we utilize data and a numerical model incorporating a five-level master equation solution to estimate the fundamental sensitivity limits of our system.