Electrically switchable Casimir forces using transparent conductive oxides

TL;DR

This paper proposes a method to modulate Casimir forces in real-time using electrical gating of transparent conductive oxides in a metal-insulator-semiconductor structure, enabling force changes detectable by atomic force microscopy.

Contribution

It introduces two configurations for in-situ Casimir force modulation via electrical gating of TCO-based MIS junctions, demonstrating significant force changes and emphasizing the importance of oxide layer control.

Findings

Force modulation > 400 pN predicted with gating

Force modulation measurable with AFM techniques

Oxide layer thickness critically influences force control

Abstract

Casimir forces between charge-neutral bodies originate from quantum vacuum fluctuations of electromagnetic fields, which exhibit a critical dependence on material's electromagnetic properties. Over the years, in-situ modulation of material's optical properties has been enabled through various means and has been widely exploited in a plethora of applications such as electro-optical modulation, transient color generation, bio- or chemical sensing, etc. Yet Casimir force modulation has been hindered by difficulty in achieving high modulation signals due to the broadband nature of the Casimir interaction. Here we propose and investigate two configurations that allow for in-situ modulation of Casimir forces through electrical gating of a metal-insulator-semiconductor (MIS) junction comprised of transparent conductive oxide (TCO) materials. By switching the gate voltage on and off, a force modulation of > 400 pN is predicted due to substantive charge carrier accumulation in the TCO layer, which can be easily measured using state-of-the-art force measurement techniques in an atomic force microscope (AFM). We further examine the influence of the oxide layer thickness on the force modulation, suggesting the importance of the fine control of the oxide layer deposition. Our work provides a promising pathway for modulating the Casimir effect in-situ with experimentally measurable force contrast.