  We propose a scheme to tailor nanostructured trapping potentials for
ultracold atoms. Our trapping scheme combines an engineered extension of
repulsive optical dipole forces at short distances and attractive
Casimir-Polder forces at long distances between an atom and a nanostructured
surface. This extended dipole force takes advantage of excited-state dressing
by plasmonically-enhanced intensity to doubly dress the ground state and create
a strongly repulsive potential with spatially tunable characteristics. In this
work, we show that, under realistic experimental conditions, this method can be
used to trap Rubidium atoms close to surfaces (tens of nanometers) or to
realize nanostructured lattices with subwavelength periods. The influence of
the various losses and heating rate mechanism in such traps is characterized.
As an example we present a near-field optical lattice with 100nm period and
study the tunability of lattice and trapping depths. Such lattices can enhance
energy scales with interesting perspectives for the simulation of
strongly-correlated physics. Our method can be extended to other atomic species
and to other near-field hybrid systems where a strong atom-light interaction
can be expected.
