Title: Control of Ultracold Photodissociation with Magnetic Fields,
Abstract: Photodissociation of a molecule produces a spatial distribution of
photofragments determined by the molecular structure and the characteristics of
the dissociating light. Performing this basic chemical reaction at ultracold
temperatures allows its quantum mechanical features to dominate. In this
regime, weak applied fields can be used to control the reaction. Here, we
photodissociate ultracold diatomic strontium in magnetic fields below 10 G and
observe striking changes in photofragment angular distributions. The
observations are in excellent qualitative agreement with a multichannel quantum
chemistry model that includes nonadiabatic effects and predicts strong mixing
of partial waves in the photofragment energy continuum. The experiment is
enabled by precise quantum-state control of the molecules.