Microscopic Quantum Friction

TL;DR

This paper develops a microscopic quantum theory of friction between ground-state atoms, revealing universal properties and the dominant role of odd-order velocity terms, especially at room temperature.

Contribution

It introduces a model-independent framework linking quantum friction to odd-parity velocity contributions and their dissipation mechanisms.

Findings

First-order velocity dependence dominates at room temperature.

Odd-parity terms are irreversible and linked to dissipation.

Universal cubic velocity dependence at zero temperature.

Abstract

We report on a microscopic theory of quantum friction. Our approach investigates the interplay between the dispersive response and the relative center-of-mass motion of two ground-state atoms. This coupling yields a quantum force, which can be expressed as a power series in the velocity. The significance of each contribution depends on its order parity: while even-order terms are reversible, odd-order terms are irreversible and only survive in the presence of an internal dissipation mechanism. In addition, we obtain general, model-independent properties for the work performed by these contributions for arbitrary scattering trajectories. These results enable an unambiguous identification of odd-parity terms with microscopic quantum friction. At room temperature, the dominant microscopic quantum friction is of first order in the velocity and presents a strong quantum character. Our microscopic theory reveals that several properties of quantum friction obtained in specific settings -- such as the cubic dependence on velocity at zero temperature -- are indeed universal features already present at the atomic scale.