Isotope effect on the Casimir force

TL;DR

This paper investigates the isotope dependence of the Casimir force, revealing a significant isotope effect in polar dielectrics due to phonon frequency shifts, which could impact nanotechnology and fundamental physics.

Contribution

It introduces a theoretical analysis showing a large isotope effect in polar dielectrics, surpassing previous estimates for metals, and provides analytical formulas for prediction.

Findings

Isotope effect over 10^(-1) in polar dielectrics

Effect arises from isotope-mass-induced phonon line shifts

Analytical formulas for isotope effect prediction

Abstract

Isotopic dependence of the Casimir force is key to probing new physics and pushing novel technologies at the micro and nanoscale, but is largely unexplored. In 2002, an isotope effect of 10^(-4) was estimated for metals -- orders of magnitude beyond the experimental resolution. Here, by employing the Lifshitz theory, we reveal a significant isotope effect of over 10^(-1) for polar dielectrics. This effect arises from the isotope-mass-induced line shift of the zone-center optical phonons and is insensitive to the linewidth. We perform numerical analyses on both the imaginary and real-frequency axes, and derive analytical formulas for predicting the isotope effect.