Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 46: Quantengase: Optische Gitter 4

Q 46.8: Vortrag

Donnerstag, 15. März 2012, 15:45–16:00, V53.01

Photodissociation of ⁴⁰K₂ Feshbach molecules — •Simon Braun¹, Liam Cook², Ulrich Schneider¹, Lucia Hackermüller³, Sebastian Will⁴, Thorsten Best⁵, Philipp Ronzheimer¹, Michael Schreiber¹, Paul Julienne⁶, and Immanuel Bloch¹ — ¹Ludwig-Maximilians-Universität München — ²University College London — ³University of Nottingham — ⁴MIT Cambridge — ⁵Universität Innsbruck — ⁶NIST Gaithersburg

One requirement to study many-body phenomena with ultracold atoms in optical lattices is a sufficiently long lifetime and low enough heating rate of the atomic samples in the optical potentials. In the case of blue-detuned optical lattice potentials, one of the main loss and heating mechanisms is given by light-assisted collisions on doubly occupied lattice sites. Due to the similarity of the two-particle on-site wavefunction to that of Feshbach molecules, light-assisted collisions directly correspond to the photodissociation of Feshbach molecules.

We present a thorough measurement of the photodissociation spectrum of ⁴⁰K₂ Feshbach molecules in a broad detuning range on the blue-detuned side of the atomic D2 transition. We compare our measurements with a multichannel calculation, obtaining excellent agreement. We obtain information about both the initial Feshbach molecule wavefunction and the exit channel Born-Oppenheimer potential and can construct an excited state potential energy model that is consistent with previous experimental observations.

The measurements enable us to choose the wavelength of our optical lattice laser such that light-assisted losses are minimized.