Phononic Casimir Effect in Planar Materials

TL;DR

This paper explores the phononic Casimir effect between planar materials, deriving a formalism to understand fluctuation-induced phonon coupling, revealing dominant polarization modes and potential for interaction control similar to electromagnetic Casimir forces.

Contribution

It introduces a formalism for the phononic Casimir effect in planar materials, highlighting the dominant polarization mode and potential for controlling phononic interactions.

Findings

Coupling dominated by one polarization mode due to exponential suppression of others

Scaling laws depend on material properties and temperature

Possible scenarios where phononic Casimir effect rivals electromagnetic Casimir force

Abstract

The Phononic Casimir effect between planar objects is investigated by deriving a formalism from the quantum partition function of the system following multiscattering approach. This fluctuation-induced coupling is mediated by phonons modeled as an effective elastic medium. We find that excitations with three types of polarizations arise from the resolved boundary conditions, however the coupling is dominated by only one of these degrees of freedom due to exponential suppression effects in the other two. The obtained scaling laws and dependence on materials properties and temperature suggest effective pathways of interaction control. Scenarios of materials combinations are envisioned where the Phononic Casimir effect is of similar order as the standard Casimir interaction mediated by electromagnetic fluctuations.