Raman-induced Spin-Orbit Coupling in Optical Superlattices

We demonstrate a new scheme for spin-orbit coupling (SOC) of ultracold atoms. Instead of internal (hyperfine) states, two lowest bands in an optical superlattice were used as pseudospins. ~A Raman process was implemented to provide coupling between pseudospin and momentum. With single internal state and far-detuned beams used, our new scheme will allow convenient generalisation to a wide range of atoms. Pseudospin interaction is tuneable by controlling the superlattice,~allowing us to study~many-body phenomena in SOC systems such as the stripe phase.