Hannover 2016 – scientific programme
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MO: Fachverband Molekülphysik
MO 4: Cold Molecules & Helium Droplets 1
MO 4.5: Talk
Monday, February 29, 2016, 15:30–15:45, f142
Direct cooling of polar molecules to sub-millikelvin temperatures — •Alexander Prehn, Martin Ibrügger, Rosa Glöckner, Martin Zeppenfeld, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching
Applications of ultracold (T<1 mK) polar molecules including ultracold chemistry, quantum simulation, and high-precision spectroscopy exploit the rich internal level structure and the electric dipole moment of the molecules. The desired use of chemically diverse species requires development of direct cooling methods. However, a versatile technique to cool molecules to the ultracold regime has been lacking.
Here, we present direct cooling of formaldehyde (H2CO) to the microkelvin regime [1]. Our approach, optoelectrical Sisyphus cooling, which was first demonstrated with methyl fluoride (CH3F) [2], provides a simple dissipative cooling method applicable to a variety of electrically trapped dipolar molecules. By reducing the temperature by three orders of magnitude and increasing the phase-space density by a factor of ∼104 we generate an ensemble of about 3·105 molecules with a temperature of about 420 µ K. In addition to producing a record-large ensemble of ultracold molecules, we have good control over the internal molecular state: the molecules in the prepared ensemble populate a single rotational state with more than 80 % purity.
[1] A. Prehn et al., arXiv:1511.09427 (2015).
[2] M. Zeppenfeld et al., Nature 491, 570 (2012).