Optical Two-dimensional Coherent Spectroscopy of Cold Atoms

TL;DR

This paper demonstrates optical two-dimensional coherent spectroscopy (2DCS) in cold rubidium atoms, enabling detailed study of many-body physics and chemical reactions at ultracold temperatures.

Contribution

First experimental implementation of optical 2DCS in cold atoms integrated with a magneto-optical trap.

Findings

Successfully obtained 1D second- and fourth-order nonlinear signals.

Acquired one-quantum and zero-quantum 2D spectra of cold Rb atoms.

Showed potential for studying many-body physics and chemical dynamics in cold systems.

Abstract

We report an experimental demonstration of optical 2DCS in cold atoms. The experiment integrates a collinear 2DCS setup with a magneto-optical trap (MOT), in which cold rubidium (Rb) atoms are prepared at a temperature of about 200 $\mu$K and a number density of $10^{10}$ cm$^{-3}$. With a sequence of femtosecond laser pulses, we first obtained one-dimensional second- and fourth-order nonlinear signals and then acquired both one-quantum and zero-quantum 2D spectra of cold Rb atoms. The capability of performing optical 2DCS in cold atoms is an important step toward optical 2DCS study of many-body physics in cold atoms and ultimately in atom arrays and trapped ions. Optical 2DCS in cold atoms/molecules can also be a new avenue to probe chemical reaction dynamics in cold molecules.