Direct frequency comb laser cooling and trapping

TL;DR

This paper introduces a novel method using optical frequency combs for laser cooling and trapping of atoms, potentially expanding ultracold atom research to elements not accessible with traditional continuous wave lasers.

Contribution

The authors demonstrate Doppler cooling and magneto-optical trapping of atoms via optical frequency combs, enabling cooling of elements like hydrogen, carbon, oxygen, and nitrogen.

Findings

Successful two-photon Doppler cooling with frequency combs

Creation of a magneto-optical trap using comb-driven cooling

Potential to cool abundant and chemically relevant atoms

Abstract

Continuous wave (CW) lasers are the enabling technology for producing ultracold atoms and molecules through laser cooling and trapping. The resulting pristine samples of slow moving particles are the de facto starting point for both fundamental and applied science when a highly-controlled quantum system is required. Laser cooled atoms have recently led to major advances in quantum information, the search to understand dark energy, quantum chemistry, and quantum sensors. However, CW laser technology currently limits laser cooling and trapping to special types of elements that do not include highly abundant and chemically relevant atoms such as hydrogen, carbon, oxygen, and nitrogen. Here, we demonstrate that Doppler cooling and trapping by optical frequency combs may provide a route to trapped, ultracold atoms whose spectra are not amenable to CW lasers. We laser cool a gas of atoms by driving a two-photon transition with an optical frequency comb, an efficient process to which every comb tooth coherently contributes. We extend this technique to create a magneto-optical trap (MOT), an electromagnetic beaker for accumulating the laser-cooled atoms for further study. Our results suggest that the efficient frequency conversion offered by optical frequency combs could provide a key ingredient for producing trapped, ultracold samples of nature's most abundant building blocks, as well as antihydrogen. As such, the techniques demonstrated here may enable advances in fields as disparate as molecular biology and the search for physics beyond the standard model.