We demonstrate a new technique for detecting components of arbitrarily-shaped radio-frequency waveforms based on stroboscopic back-action evading measurements. We combine quantum non-demolition measurements and stroboscopic probing to detect waveform components with magnetic sensitivity beyond the standard quantum limit. Using an ensemble of 1.5×106 cold rubidium atoms, we demonstrate entanglement-enhanced sensing of sinusoidal and linearly chirped waveforms, with 1.0(2)dB and 0.8(3)dB metrologically relevant noise reduction, respectively. We achieve volume-adjusted sensitivity of δBV≈11.20fTcm3/Hz, comparable to the best RF~magnetometers.
@article{arxiv.1702.08294,
title = {Entanglement-enhanced radio-frequency field detection and waveform sensing},
author = {F. Martin Ciurana and G. Colangelo and L. Slodicka and R. J. Sewell and M. W. Mitchell},
journal= {arXiv preprint arXiv:1702.08294},
year = {2017}
}