Plane waves as tractor beams

TL;DR

This paper demonstrates that in certain physical systems, plane waves can exert a pulling force on objects, acting as tractor beams due to mode scattering influenced by gauge potentials, including artificial ones.

Contribution

It reveals that plane waves can function as tractor beams through mode scattering mechanisms involving gauge potentials, expanding understanding of negative radiation pressure effects.

Findings

Plane waves can exert pulling forces on scatterers.

Strong scattering into higher wave number modes causes the effect.

Gauge potentials, including artificial ones, facilitate the tractor beam phenomenon.

Abstract

It is shown that in a large class of systems plane waves can act as tractor beams: i.e., an incident plane wave can exert a pulling force on the scatterer. The underlying physical mechanism for the pulling force is due to the sufficiently strong scattering of the incoming wave into another mode having a larger wave number, in which case excess momentum is created behind the scatterer. Such a tractor beam or negative radiation pressure effect arises naturally in systems where the coupling between the scattering channels is due to Aharonov-Bohm (AB) gauge potentials. It is demonstrated that this effect is also present if the AB potential is an induced, ("artificial") gauge potential such as the one found in J. March-Russell, J. Preskill, F. Wilczek, Phys. Rev. Lett. 58 2567 (1992).