Probing light forces on cold atoms by noise correlation spectroscopy

Abstract

Enhanced sensitivity in electromagnetically induced transparency (EIT) can be obtained by the use of noise correlation spectroscopy between the fields involved in the process. Here, we investigate EIT in a cold (< 1 mK) rubidium vapor and demonstrate sensitivity to detect weak light-induced forces on the atoms. A theoretical model is developed and shows good agreement with our measurements, enabling the attribution of the observed effects to the coupling of the atomic states to their motion. The effects remain unnoticed on the measurement of the mean fields but are clearly manifest in their correlations.

Noise spectroscopy in Rydberg atomic ensemble

“…At lower frequency range, the signal-tonoise ratio (SNR) for spectroscopy is limited by classical sources of mechanical and audio noise. At higher frequencies, the sensitivity is limited by the quantum noise of photons and atomic ensembles [7][8][9][10][11][12]. Rydberg-atom sensing relies on an electromagnetically induced transparency (EIT)-based method, in which various laser fields are required to perform internal quantum state manipulations.…”

“…To improve sensing sensitivity, the EIT parameters are controlled to operate under weak excitation conditions. Noise in the intensity of laser beams may be suppressed through a combination of averaging and differential detection [11,12]. However, phase noise of the laser beams remains strong and introduces measurable noise.…”