Rydberg molecule-induced remote spin-flips
  We have performed high resolution photoassociation spectroscopy of rubidium ultra long-range Rydberg molecules in the vicinity of the 25$P$ state. Due to the hyperfine interaction in the ground state perturber atom, the emerging mixed singlet-triplet potentials contain contributions from both hyperfine states. We show that this can be used to induce remote spin-flips in the perturber atom upon excitation of a Rydberg molecule. When furthermore the spin-orbit splitting of the Rydberg state is comparable to the hyperfine splitting in the ground state, the orbital angular momentum of the Rydberg electron is entangled with the nuclear spin of the perturber atom. Our results open new possibilities for the implementation of spin-dependent interactions for ultracold atoms in bulk systems and in optical lattices. 
Thomas Niederpr\"um and Oliver Thomas and Tanita Eichert and Herwig   Ott
physics.atom-ph physics.chem-ph quant-ph