Two-temperature momentum distribution in a Thulium magneto-optical trap

Abstract

Second-stage laser cooling of thulium atoms at the 530.7 nm transition with a natural linewidth of 350 kHz offers an interesting possibility to study different regimes of a magneto-optical trap (MOT). The intermediate value of the spectral linewidth of the cooling transition allows the observation of three distinct regimes depending on intensity and detuning of the cooling beams. Namely, the "bowl-shaped" regime when light pressure force competes with gravity, the "double structure" regime with interplay between Doppler and polarization-gradient (sub-Doppler) cooling, and the "symmetric" regime when Doppler cooling dominates over sub-Doppler cooling and gravity. The polarization-gradient cooling manifests itself by a two-temperature momentum distribution of atoms resulting in a double-structure of the spatial MOT profile consisting of a cold central fraction surrounded by a hot halo. We studied the "double structure" regime at different saturation parameters and compared observations with calculations based on semiclassical and quantum approaches. The quantum treatment adequately reproduces experimental results if the MOT magnetic field is properly taken into account.

7 pages, 6 figures

References in corpus (7)

• d-wave collapse and explosion of a dipolar Bose-Einstein condensate
• Magneto-Optical Trap for Thulium Atoms
• Observation of Fermi surface deformation in a dipolar quantum gas
• Dysprosium magneto-optical traps
• Narrow-line magneto-optical cooling and trapping of strongly magnetic atoms
• Sub-Doppler laser cooling and magnetic trapping of erbium
• Anisotropic sub-Doppler laser cooling in dysprosium magneto-optical traps

Cited by in corpus (6)

• Dissipative pure-optical trap for laser cooling and trapping of neutral atoms
• Sub-nanometer optical linewidth of thulium atoms in rare gas crystals
• Deep Laser Cooling of Thulium Atoms to Sub-$\mu$K Temperatures in Magneto-Optical Trap
• Inspiration from machine learning on example of optimization of the Bose-Einstein condensate of thulium atoms in a 1064-nm trap
• Sub-Doppler cooling of bosonic strontium in a two-color MOT
• Transport of magnetically sensitive atoms in a magnetic environment