Genuine multipartite entanglement and Einstein-Podolsky-Rosen steering of atomic clouds
I will report on recent experiments in the group of Markus Oberthaler on the generation and detection of entanglement between spatially separated parts of an atomic cloud.
To generate a squeezed vacuum state, we use spin mixing in a tightly confined Bose-Einstein condensate of 87Rb in a single spatial mode. We show experimentally that the corresponding particle entanglement can be spatially distributed by self-similar expansion of the atomic cloud in a waveguide potential. Spatially resolved spin read-out is used to reveal Einstein-Podolsky-Rosen (EPR) steering between distinct parts of the expanded cloud. To quantify the connection between the strength of EPR steering and genuine multipartite entanglement we construct a witness, which testifies up to genuine five-partite entanglement.