Tunable Casimir repulsion with three dimensional topological insulators

TL;DR

This paper demonstrates that by tuning external parameters, one can switch between repulsive and attractive Casimir forces using topological insulator plates, with a critical distance where forces cancel out.

Contribution

It introduces a method to control Casimir forces via tunable parameters in topological insulators, revealing regimes of repulsion and attraction at different distances.

Findings

Repulsive and attractive Casimir regimes depend on distance.

A critical distance exists where Casimir force cancels.

Force behavior is linked to electromagnetic response of topological insulators.

Abstract

In this Letter, we show that switching between repulsive and attractive Casimir forces by means of external tunable parameters could be realized with two topological insulator plates. We find two regimes where a repulsive (attractive) force is found at small (large) distances between the plates, canceling out at a critical distance. For a frequency range where the effective electromagnetic action is valid, this distance appears at length scales corresponding to $1-\epsilon(\omega) (2/\pi)\alpha\theta$.