The quest for ultracold ground state molecules
Standard laser cooling techniques as developed for atoms do not work
for molecules due
The weakly bound Feshbach molecules (upper image) are transferred into the rovibrational ground state with a STIRAP laser pulse.
Very recently optical schemes have been developed to selectively produce cold and dense samples of deeply bound molecules in the ro-vibrational ground state, but this goal has not been reached yet. We report here the optical transfer of 87Rb2 Feshbach molecules to a single quantum level in the ro-vibrational ground state of the Rb2 triplet potential (a 3Σu+ ), entering the regime of an ultracold and dense ensemble of tightly bound molecules .
Potential curves of the ground (a 3Σu+) and excited (3Σg) molecular triplet potential.
The transfer is carried out in a single step using stimulated Raman adiabatic passage (STIRAP) with an efficiency of almost 90%, which is only technically limited. The molecules are held in a 3D optical lattice in which they exhibit a trap lifetime exceeding 200 ms, after an initial relaxation within 50 ms.
Simon Cornish from the university of Durham has written a viewpoint article on our and related work: S. Cornish, Physics 1, 24 (2008).
Innsbruck press release
The research team
This research was carried out by the Rb-team in the Group of Rudi Grimm under the scientific lead of Johannes Hecker Denschlag.
from left to right: R. Grimm, J. Hecker Denschlag, Tetsu Takekoshi, F. Lang, K. Winkler & C. Strauss
We are supported by the Austrian Science Fund (Fonds zur Förderung der wissenschaftlichen Forschung, FWF) in the frame of the Spezialforschungsbereich F15 "Control and Measurement of Coherent Quantum Systems" and by the European Union in the frame of the Cold Molecules TMR Network.
last change: 08-09-27 by FL