Narrow-line laser cooling by adiabatic transfer

Author
Abstract
<p>We propose and demonstrate a novel laser cooling mechanism applicable to particles with narrow-linewidth optical transitions. By sweeping the frequency of counter-propagating laser beams in a sawtooth manner, we cause adiabatic transfer back and forth between the ground state and a long-lived optically excited state. The time-ordering of these adiabatic transfers is determined by Doppler shifts, which ensures that the associated photon recoils are in the opposite direction to the particle\textquoterights motion. This ultimately leads to a robust cooling mechanism capable of exerting large forces via a weak transition and with reduced reliance on spontaneous emission. We present a simple intuitive model for the resulting frictional force, and directly demonstrate its efficacy for increasing the total phase-space density of an atomic ensemble. We rely on both simulation and experimental studies using the 7.5 kHz linewidth\&nbsp;1S0\&nbsp;to\&nbsp;3P1\&nbsp;transition in\&nbsp;88Sr. The reduced reliance on spontaneous emission may allow this adiabatic sweep method to be a useful tool for cooling particles that lack closed cycling transitions, such as molecules.</p>
Year of Publication
2018
Journal
New J. Phys.
Volume
20
Number of Pages
023021
Date Published
2018-02
URL
http://iopscience.iop.org/article/10.1088/1367-2630/aaa950/meta
DOI
https://doi.org/10.1088/1367-2630/aaa950
JILA PI
Associated Institutes
Journal Article