Sub-Diffractive Band-Edge Solitons in Bose-Einstein Condensates in Periodic Potentials

TL;DR

This paper introduces a novel matter wave diffraction management in Bose-Einstein condensates using counter-moving optical lattices, resulting in sub-diffractive soliton-like structures due to a unique atomic band-gap with infinite effective mass.

Contribution

It presents a new diffraction management technique that creates sub-diffractive solitons by engineering atomic band structures with infinite effective mass at the band edge.

Findings

Discovery of a band-gap with infinite effective mass at the lowest energy edge.

Normal diffraction is replaced by fourth-order diffraction in the system.

The system exhibits sub-diffractive propagation of matter waves.

Abstract

A new type of matter wave diffraction management is presented that leads to sub-diffractive soliton-like structures. The proposed management technique uses two counter-moving, identical periodic potentials (e.g. optical lattices). For suitable lattice parameters a novel type of atomic band-gap structure appears in which the effective atomic mass becomes infinite at the lowest edge of an energy band. This way normal matter-wave diffraction (proportional to the square of the atomic momentum) is replaced by fourth-order diffraction, and hence the evolution of the system becomes sub-diffractive.