  We load cold atoms into an optical lattice dramatically reshaped by
radiofrequency (rf) coupling of state-dependent lattice potentials. This rf
dressing changes the unit cell of the lattice at a subwavelength scale, such
that its curvature and topology departs strongly from that of a simple
sinusoidal lattice potential. Radiofrequency dressing has previously been
performed at length scales from mm to tens of microns, but not at the
single-optical-wavelength scale. At this length scale significant coupling
between adiabatic potentials leads to nonadiabatic transitions, which we
measure as a function of lattice depth and dressing frequency and amplitude. We
also investigate the dressing by measuring changes in the momentum distribution
of the dressed states.
