Heidelberg 2015 – scientific programme
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A: Fachverband Atomphysik
A 34: Ultracold Atoms: Trapping and Cooling II (with Q)
A 34.7: Talk
Thursday, March 26, 2015, 16:00–16:15, P/H2
Implementation of Λ-enhanced gray-molasses cooling for 40K — •Matthias Tarnowski, Nick Fläschner, Dominik Vogel, Benno Rem, Christof Weitenberg, and Klaus Sengstock — Institut für Laserphysik, Uni Hamburg
Sub-Doppler cooling is an important step to reach quantum degeneracy in atomic gases. It has recently been demonstrated that the Λ-enhanced gray-molasses scheme leads to much lower temperatures than expected for alkali atoms. Here, we present a detailed study of a blue-detuned gray-molasses cooling scheme for fermionic 40K on the D1 transition. We find that the Raman resonance condition between the cooling and repumping frequency in a Λ-type system has indeed to be fulfilled to observe the anticipated narrow feature of very low temperatures around the resonance. With optimal parameters we achieve a temperature of 6 µK. In combination with repumping and optical pumping on the D1 transition we realize efficient loading of a K-Rb mixture into a magnetic trap and fast subsequent evaporation. We significantly reduce the cycle time of our experimental sequence compared to cooling on the D2 transition. Our results demonstrate ideal starting conditions for all-optical production of potassium degenerate gases.