Quantum friction and fluctuation theorems

TL;DR

This paper derives the quantum frictional force on an atom near a surface using statistical mechanics, revealing it scales cubically with velocity at zero temperature, and critiques common approximation methods.

Contribution

It introduces a non-equilibrium fluctuation-dissipation approach to accurately compute quantum friction and highlights limitations of traditional approximations.

Findings

Quantum friction scales as velocity cubed at zero temperature.

Standard approximations like Wigner-Weisskopf fail to predict correct friction.

The derived force applies in the large-time steady-state regime.

Abstract

We use general concepts of statistical mechanics to compute the quantum frictional force on an atom moving at constant velocity above a planar surface. We derive the zero-temperature frictional force using a non-equilibrium fluctuation-dissipation relation, and show that in the large-time, steady-state regime quantum friction scales as the cubic power of the atom's velocity. We also discuss how approaches based on Wigner-Weisskopf and quantum regression approximations fail to predict the correct steady-state zero temperature frictional force, mainly due to the low frequency nature of quantum friction.