Unidirectional transport of wave packets through tilted discrete breathers in nonlinear lattices with asymmetric defects

TL;DR

This paper demonstrates unidirectional wave packet transport through tilted discrete breathers in nonlinear lattices with asymmetric defects, revealing a tractor-beam effect and potential applications in atomic and optical beam control.

Contribution

It introduces a unidirectional transport mode in nonlinear lattices with asymmetric defects, supported by analytical energy barrier analysis, and highlights the tractor-beam effect in wave packet scattering.

Findings

Unidirectional wave packet transmission occurs within specific energy intervals.

The TDB shifts by one lattice unit during passage, demonstrating a tractor-beam effect.

The system enables rectification and unidirectional propagation of waves.

Abstract

We consider the transfer of lattice wave packets through a tilted discrete breather (TDB) in opposite directions in the discrete nonlinear Schr\"{o}dinger model with asymmetric defects, which may be realized as a Bose-Einstein condensate trapped in a deep optical lattice, or as optical beams in a waveguide array. A unidirectional transport mode is found, in which the incident wave packets, whose energy belongs to a certain interval between full reflection and full passage regions, pass the TDB only in one direction, while, in the absence of the TDB, the same lattice admits bi-directional propagation. The operation of this mode is accurately explained by an analytical consideration of the respective energy barriers. The results suggest that the TDB may emulate the unidirectional propagation of atomic and optical beams in various settings. In the case of the passage of the incident wave packet, the scattering TDB typically shifts by one lattice unit in the direction from which the wave packet arrives, which is an example of the tractor-beam effect, provided by the same system, in addition to the rectification of incident waves.