# Measurement of non-monotonic Casimir forces between silicon nanostructures

## TL;DR

This study experimentally demonstrates non-monotonic Casimir forces between silicon nanostructures, revealing complex force behaviors that could enable advanced control in nanomechanical systems.

## Contribution

The paper introduces an on-chip platform that measures non-monotonic Casimir forces between nanostructures, overcoming alignment challenges in previous experiments.

## Key findings

- Casimir force depends non-monotonically on displacement
- Force can cause effective stiffening of nanomechanical springs
- Demonstrates control of Casimir forces in complex geometries

## Abstract

Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field. Apart from controlling the Casimir force via the optical properties of the materials, a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps. Experimental realization of these geometries, however, is hindered by the difficulties in alignment when the bodies are brought into close proximity. Here, using an on-chip platform with integrated force sensors and actuators, we circumvent the alignment problem and measure the Casimir force between two surfaces with nanoscale protrusions. We demonstrate that the Casimir force depends non-monotonically on the displacement. At some displacements, the Casimir force leads to an effective stiffening of the nanomechanical spring. Our findings pave the way for exploiting the Casimir force in nanomechanical systems using structures of complex and non-conventional shapes.

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Source: https://tomesphere.com/paper/1701.02351