Two trap technologies combine to keep ions locked in place. (Top) The potential an ion experiences in a quadrupole trap is relatively flat on the submicrometer scale. An external or stray electric field can easily displace the ion by hundreds of nanometers, limiting the stability of the trap. (Bottom) An optical lattice superimposed on the ion-trap potential provides a periodic structure on the scale of optical wavelengths. An ion is localized at a single valley of the lattice and remains pinned even in the presence of the electric field.