Sub-Doppler laser cooling of 40K with Raman gray molasses on the D2 line

Graham David Bruce, Elmar Haller, Bruno Peaudecerf, Dylan A Cotta, Manuel Andia, Saijun Wu, Matthew Y H Johnson, Brendon William Lovett, Stefan Kuhr

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17 Citations (Scopus)
19 Downloads (Pure)


Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to low temperatures. For alkaline atoms, this technique is commonly implemented with cooling lasers which are blue-detuned from either the D1 or D2 line. Here we show that efficient gray molasses can be implemented on the D2 line of 40K with red-detuned lasers. We obtained temperatures of 48(2)µK, which enables direct loading of 9.2(3)x106 atoms from a magneto-optical trap into an optical dipole trap. We support our findings by a one-dimensional model and three-dimensional numerical simulations of the optical Bloch equations which qualitatively reproduce the experimentally observed cooling effects.
Original languageEnglish
Article number095002
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Issue number9
Publication statusPublished - 12 Apr 2017


  • Atomic physics
  • Gray molasses
  • Laser cooling
  • Ultracold atoms
  • sub-Doppler cooling


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