  The formation of ultralong-range Rydberg molecules is a result of the
attractive interaction between Rydberg electron and polarizable ground state
atom in an ultracold gas. In the nondegenerate case the backaction of the
polarizable atom on the electronic orbital is minimal. Here we demonstrate, how
controlled degeneracy of the respective electronic orbitals maximizes this
backaction and leads to stronger binding energies and lower symmetry of the
bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular
bond.
