Light-shift induced behaviors observed in momentum-space quantum walks

TL;DR

This paper presents a theoretical model explaining previously unexplained behaviors in momentum-space quantum walks observed in spinor Bose-Einstein condensates, emphasizing the role of coherent dynamics and eliminating the need for thermal cloud considerations.

Contribution

The authors develop a new theoretical model that accurately explains experimental momentum distributions in quantum walks without assuming thermal clouds, enhancing understanding of quantum search and topological phases.

Findings

Coherent dynamics explain experimental data without thermal clouds.

Analytical predictions match numerical simulations for zero-temperature condensates.

Model applies to quantum search algorithms and Floquet systems.

Abstract

Over the last decade there have been many advances in studies of quantum walks (QWs) including a momentum-space QW recently realized in our spinor Bose-Einstein condensate system. This QW possessed behaviors that generally agreed with theoretical predictions; however, it also showed momentum distributions that were not adequately explained by the theory. We present a theoretical model which proves that the coherent dynamics of the spinor condensate is sufficient to explain the experimental data without invoking the presence of a thermal cloud of atoms as in the original theory. Our numerical findings are supported by an analytical prediction for the momentum distributions in the limit of zero-temperature condensates. This current model provides more complete explanations to the momentum-space QWs that can be applied to study quantum search algorithms and topological phases in Floquet-driven systems.