# Entanglement-enhanced radio-frequency field detection and waveform sensing

## TL;DR

This paper presents a quantum-enhanced technique for detecting complex radio-frequency waveforms using entanglement and stroboscopic measurements, surpassing standard quantum limits in sensitivity.

## Contribution

It introduces a novel method combining quantum non-demolition and stroboscopic probing for waveform detection with entanglement-enhanced sensitivity.

## Key findings

- Achieved 1.0 dB and 0.8 dB noise reduction in waveform sensing.
- Demonstrated sensitivity comparable to the best RF magnetometers.
- Used an ensemble of 1.5 million cold rubidium atoms.

## Abstract

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 $1.5\times 10^6$ 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 $\delta\rm{B}\sqrt{V}\approx 11.20~\rm{fT\sqrt{cm^3/Hz}}$, comparable to the best RF~magnetometers.