Trapping and cooling mechanisms in blue-detuned magnetooptical traps of molecules
File(s)
Published version
Author(s)
Lyu, Qinshu
Tarbutt, Michael
Type
Journal Article
Abstract
In red-detuned magneto-optical traps (MOTs) of molecules, sub-Doppler heating competes with Doppler cooling, resulting in high temperature and low density. A solution is offered by the blue-detuned MOT where sub-Doppler cooling dominates and the cloud is compressed. Several blue-detuned molecular MOTs have been implemented. A recent implementation relies on a pair of orthogonally polarized components whose frequency separation is smaller than the transition linewidth. We identify the trapping force in these MOTs. At a certain magnetic field, there is a state that is dark to the laser propagating in one direction, but not to the counter-propagating one. This Zeeman-induced dark state (ZIDS) sets up an imbalance in the photon scattering rate, leading to a restoring force. We also study the role of the moving lattices generated by the closely-spaced frequency components of the light. We show that there is a velocity-dependent force that drives the molecules towards the speeds of these moving lattices, and that over a relevant range of magnetic fields this combines with the ZIDS force to transport molecules towards the centre of the MOT. Here, gray molasses cooling, assisted by non-adiabatic transitions driven by the time-varying polarization of the light field, cools the molecules towards zero velocity. We study these mechanisms for model systems with simple level structures, then extend them to molecules with ground state hyperfine structure.
Date Issued
2026-06-01
Date Acceptance
2026-05-03
Citation
Physical Review Research, 2026, 8 (2)
ISSN
2643-1564
Publisher
American Physical Society
Journal / Book Title
Physical Review Research
Volume
8
Issue
2
Copyright Statement
© The Author(s) 2026. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
License URL
Identifier
10.1103/ctj6-6hg9
Publication Status
Published
Article Number
ARTN 023259
Date Publish Online
2026-06-08