Broadband Optical Two-Dimensional Coherent Spectroscopy of a Rubidium Atomic Vapor

TL;DR

This paper demonstrates broadband optical two-dimensional coherent spectroscopy on rubidium vapor, capturing comprehensive spectra of both D-lines and enabling advanced studies of atomic interactions and correlations.

Contribution

It presents the first broadband 2DCS experiment on rubidium atoms covering both D-lines, including double-quantum spectra, and compares experimental results with simulations.

Findings

Successfully obtained complete 2D spectra of Rb D-lines

Reproduced spectra with optical Bloch equation simulations

Enabled double-quantum and multi-quantum 2DCS for Rb atoms

Abstract

Optical two-dimensional coherent spectroscopy (2DCS) has become a powerful tool for studying energy level structure, dynamics, and coupling in many systems including atomic ensembles. Various types of two-dimensional (2D) spectra, including the so-called single-quantum, zero-quantum, and double-quantum 2D spectra, of both D lines (D$_1$ and D$_2$ transitions) of potassium (K) atoms have been reported previously. For rubidium (Rb), a major difference is that the D-lines are about 15 nm apart as opposed to only about 3 nm for K. Simultaneously exciting both D-lines of Rb atoms requires a broader laser bandwidth for the experiment. Here, we report a broadband optical 2DCS experiment in an Rb atomic vapor. A complete set of single-quantum, zero-quantum, and double-quantum 2D spectra including both D-lines of Rb atoms were obtained. The experimental spectra were reproduced by simulated 2D spectra based on the perturbation solutions to the optical Bloch equations. This work in Rb atoms complements previous 2DCS studies of K and Rb with a narrower bandwidth that covers two D-lines of K or only a single D-line of Rb. The broadband excitation enables the capability to perform double-quantum and multi-quantum 2DCS of both D-lines of Rb to study many-body interactions and correlations in comparison with K atoms.