Molecular Feshbach dissociation as a source for motionally entangled atoms

We describe the dissociation of a diatomic Feshbach molecule due to a time-varying external magnetic field in a realistic trap and guide setting. An analytic expression for the asymptotic state of the two ultracold atoms is derived, which can serve as a basis for the analysis of dissociation protocols to generate motionally entangled states. For instance, the gradual dissociation by sequences of magnetic field pulses may delocalize the atoms into macroscopically distinct wave packets, whose motional entanglement can be addressed interferometrically. The established relation between the applied magnetic field pulse and the generated dissociation state reveals that square-shaped magnetic field pulses minimize the momentum spread of the atoms. This is required to control the detrimental influence of dispersion in a recently proposed experiment to perform a Bell test in the motion of the two atoms [C. Gneiting and K. Hornberger, Phys. Rev. Lett. 101, 260503 (2008)].

Hunds paradox and the collisional stabilization of chiral molecules

We identify the dominant collisional decoherence mechanism which serves to stabilize and super-select the configuration states of chiral molecules. A high-energy description of this effect is compared to the results of the exact molecular scattering problem, obtained by solving the coupled-channel equations. It allows to predict the experimental conditions for observing the collisional suppression of the tunneling dynamics between the left-handed and the right-handed configuration of D2S2 molecules.