Realization of a fractional period adiabatic superlattice

We propose and realize a deeply sub-wavelength optical lattice for ultracold neutral atoms using Nresonantly Raman-coupled internal degrees of freedom. Although counter-propagating lasers with wavelength \lambdaprovided two-photon Raman coupling, the resultant lattice-period was \lambda/2N an Nfold reduction as compared to the conventional \lambda/2lattice period. We experimentally demonstrated this lattice built from the three...