Frequency-comb based double-quantum two-dimensional coherent spectroscopy identifies collective hyperfine resonances in atomic vapor induced by dipole-dipole interactions

TL;DR

This paper demonstrates a novel frequency comb based double-quantum 2D spectroscopy technique that reveals collective hyperfine resonances in rubidium vapor, showing tilted lineshapes indicative of dipole-dipole interactions among near-zero velocity atoms.

Contribution

It introduces a high-resolution, rapid acquisition multidimensional spectroscopy method for atomic vapors and uncovers new spectral features related to dipole-dipole interactions.

Findings

Revealed collective hyperfine resonances in rubidium vapor.

Observed tilted lineshapes in double-quantum spectra.

Indicated interactions primarily from atoms with near zero relative velocity.

Abstract

Frequency comb based multidimensional coherent spectroscopy is a novel optical method that enables high resolution measurement in a short acquisition time. The method's resolution makes multidimensional coherent spectroscopy relevant for atomic systems that have narrow resonances. We use double-quantum multidimensional coherent spectroscopy to reveal collective hyperfine resonances in rubidium vapor at 100 C induced by dipole-dipole interactions. We observe tilted lineshapes in the double-quantum 2D spectra, which has never been reported for Doppler-broadened systems. The tilted lineshapes suggest that the signal is predominately from the interacting atoms that have near zero relative velocity.