Light shift induced behaviors observed in momentum-space quantum walks

Quantum walks (QWs) have seen many advances both experimentally and theoretically over the last decade with many proposed applications. Recently, a QW was experimentally realized utilizing a Bose-Einstein Condensate (BEC) in momentum space. This QW was observed to be stable up to fifteen steps and exhibited behavior that agreed generally well with theoretical predictions. However, the QW also showed interesting behavior within the momentum distribution that wasn’t adequately explained by the theory. We propose a new theoretical model to offer an explanation based upon the parameters within the conducted experiments. This model also predicts that the discrepancy is dependent upon the initial momentum states used in creating the QW.