Realization of a deeply subwavelength adiabatic optical lattice

We propose and describe our realization of a deeply subwavelength optical lattice for ultracold neutral atoms using N resonantly Raman-coupled internal degrees of freedom. Although counterpropagating lasers with wavelength. provided two-photon Raman coupling, the resultant lattice period was lambda/2N, an N-fold reduction as compared to the conventional lambda/2 lattice period. We experimentally demonstrated this lattice built from the three F = 1 Zeeman states of a Rb-87 Bose-Einstein condensate, and generated a lattice with a lambda/6 = 132 nm period from lambda = 790 nm lasers. Lastly, we show that adding an additional rf-coupling field converts this lattice into a superlattice with N wells uniformly spaced within the original lambda/2 unit cell.