Inhomogeneity-Induced Casimir Transport of Nanoparticles

TL;DR

This paper introduces a novel quantum vacuum fluctuation-based method for nanoparticle transport using inhomogeneity-induced Casimir forces, enabling size-selective and tunable movement near metasurfaces.

Contribution

It presents a new mechanism for nanoparticle transport leveraging inhomogeneity-induced Casimir forces and relaxes previous constraints, broadening material applicability.

Findings

Transport velocity up to a few microns per minute.

Identification of a 'Casimir passage' with peak velocity.

Shape-dependent tuning of Casimir interactions for control.

Abstract

This letter proposes a scheme for transporting nanoparticles immersed in a fluid, relying on quantum vacuum fluctuations. The mechanism lies in the inhomogeneity-induced lateral Casimir force between a nanoparticle and a gradient metasurface, and the relaxation of the conventional Dzyaloshinski\v{i}-Lifshitz-Pitaevski\v{i} constraint, which allows quantum levitation for a broader class of material configurations. The velocity for a nanosphere levitated above a grating is calculated and can be up to a few microns per minute. The Born approximation gives general expressions for the Casimir energy which reveal size-selective transport. For any given metasurface, a certain particle-metasurface separation exists where the transport velocity peaks, forming a "Casimir passage". The sign and strength of the Casimir interactions can be tuned by the shapes of liquid-air menisci, potentially allowing real-time control of an otherwise passive force, and enabling interesting on-off or directional switching of the transport process.