  We report the optical trapping of multiple ions localized at individual
lattice sites of a one-dimensional optical lattice. We observe a fivefold
increase in robustness against axial DC-electric fields and an increase of the
axial eigenfrequency by two orders of magnitude compared to an optical dipole
trap without interference but similar intensity. Our findings motivate an
alternative pathway to extend arrays of trapped ions in size and dimension,
enabling quantum simulations with particles interacting at long range.
