Strong geometry dependence of the Casimir force between interpenetrated rectangular gratings

TL;DR

This study demonstrates that the Casimir force between interpenetrated rectangular gratings exhibits a strong geometry dependence, significantly deviating from traditional approximations and enabling new control in nanomechanical systems.

Contribution

The paper provides the first experimental measurement of the Casimir force in interpenetrating rectangular gratings, revealing a strong geometry dependence beyond previous models.

Findings

Force deviations up to ~500 times from proximity force approximation

Casimir force becomes non-zero and displacement-independent after interpenetration

Enhanced control of nanomechanical interactions via grating geometry

Abstract

Quantum fluctuations give rise to Casimir forces between two parallel conducting plates, the magnitude of which increases monotonically as the separation decreases. By introducing nanoscale gratings to the surfaces, recent advances have opened opportunities for controlling the Casimir force in complex geometries. Here, we measure the Casimir force between two rectangular gratings in regimes not accessible before. Using an on-chip detection platform, we achieve accurate alignment between the two gratings so that they interpenetrate as the separation is reduced. Just before interpenetration occurs, the measured Casimir force is found to have a geometry dependence that is much stronger than previous experiments, with deviations from the proximity force approximation reaching a factor of ~500. After the gratings interpenetrate each other, the Casimir force becomes non-zero and independent of displacement. This work shows that the presence of gratings can strongly modify the Casimir force to control the interaction between nanomechanical components.