Narrow-line laser cooling by adiabatic transfer

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 optica...

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Bibliographic Details
Published in:New journal of physics 2018-02, Vol.20 (2), p.23021
Main Authors: Norcia, Matthew A, Cline, Julia R K, Bartolotta, John P, Holland, Murray J, Thompson, James K
Format: Article
Language:English
Subjects:
Adiabatic flow
Computer simulation
Cooling
Laser beams
Laser cooling
Lasers
molecule cooling
Physics
Space density
Spontaneous emission
strontium
Strontium 88
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Summary: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's 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 1S0 to 3P1 transition in 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.
ISSN:1367-2630
1367-2630
DOI:10.1088/1367-2630/aaa950