Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080 (United States)
Magneto-optical traps (MOTs) of Er and Dy have recently been shown to exhibit populationwide sub-Doppler cooling due to their near degeneracy of excited- and ground-state Landeg factors. We discuss here an additional, unusual intra-MOT sub-Doppler cooling mechanism that appears when the total Dy MOT cooling laser intensity and magnetic quadrupole gradient increase beyond critical values. Specifically, anisotropically sub-Doppler-cooled cores appear, and their orientation with respect to the quadrupole axis flips at a critical ratio of the MOT laser intensity along the quadrupole axis versus that in the plane of symmetry. This phenomenon can be traced to a loss of the velocity-selective resonance at zero velocity in the cooling force along directions in which the atomic polarization is oriented by the quadrupole field. We present data characterizing this anisotropic laser cooling phenomenon and discuss a qualitative model for its origin based on the extraordinarily large Dy magnetic moment and Dy's near degenerate g factors.
- OSTI ID:
- 21450797
- Journal Information:
- Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 82; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANISOTROPY
COOLING
DIMENSIONLESS NUMBERS
DYSPROSIUM
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
ERBIUM
EXCITED STATES
GROUND STATES
LANDE FACTOR
LASER RADIATION
LASERS
MAGNETIC MOMENTS
MAGNETO-OPTICAL EFFECTS
METALS
ORIENTATION
POLARIZATION
RADIATIONS
RARE EARTHS
RESONANCE
SYMMETRY
TRAPS
VELOCITY