Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Dynamics in a Two-Level Atom Magneto-Optical Trap



X Xu, T Loftus, M J. Smith, John L. Hall, Alan Gallagher, Jun Ye


Alkaline earth metal atoms present an ideal platform for exploring magneto-optic trap (MOT) dynamics, enabling unique and definitive tests of laser cooling and trapping mechanisms. We have measured the trapping beam intensity, detuning, magnetic-field, gradient, trap density, and lifetime dependence of the spring constant k and damping coefficients (alpha) for a 1S0-u1^P188Sr MOT by fitting the oscillatory response of the atom cloud to a setup-function force. We find that the observed behavior of K and α provide a unified and consistent picture of trap dynamics that agrees with Doppler cooling theory at the level of 10%. Additionally, we demonstrate that the trapped atom temperature can be determined directly from measured value of K and trap size, in excellent agreement with the free-expansion temperature measurements. However, the experimentally determined temperature is much higher than Doppler cooling theory, implying significant additional heating mechanisms.
Physical Review A (Atomic, Molecular and Optical Physics)
No. 1


cold atoms, Doppler cooling, MOT, trap dynamics


Xu, X. , Loftus, T. , Smith, M. , Hall, J. , Gallagher, A. and Ye, J. (2002), Dynamics in a Two-Level Atom Magneto-Optical Trap, Physical Review A (Atomic, Molecular and Optical Physics) (Accessed December 11, 2023)
Created June 30, 2002, Updated October 12, 2021