Energetics of quantum vacuum friction. II: Dipole fluctuations and field fluctuations

TL;DR

This paper investigates quantum vacuum friction on a dissipative particle, deriving conditions for nonequilibrium steady states, and demonstrating that the friction acts as a true drag, with implications for energy exchange and experimental detection.

Contribution

It introduces a comprehensive analysis of quantum vacuum friction including dipole fluctuations, derives NESS conditions, and explores the thermodynamics and experimental signatures of the effect.

Findings

Quantum vacuum friction acts as a true drag force.

The NESS temperature depends on radiation temperature and particle velocity.

Deviations from NESS lead to energy exchange, returning the particle to NESS.

Abstract

As a second paper in series with arXiv:2108.01539, we discuss here quantum vacuum friction on an intrinsically dissipative particle. The friction arises not only from the field fluctuations but also from the dipole fluctuations intrinsic to the particle. As a result, the dissipative particle can be out of the nonequilibrium steady state (NESS), where it loses or gains internal energy. Only if the temperature of the particle equals a special NESS temperature will the particle be in NESS. We first derive the NESS conditions which give the NESS temperature of the particle as a function of the radiation temperature and the velocity of the particle. Imposing the NESS conditions, we then obtain an expression for the quantum vacuum friction in NESS. The NESS quantum vacuum friction is shown to be always negative definite, therefore a true drag. The NESS temperature and quantum vacuum friction are calculated numerically for various models. Out of NESS, even though the quantum vacuum frictional force no longer has a definite sign in the rest frame of the radiation, we find the external force needed to keep the particle moving must be in the same direction as the motion of the particle. This then excludes the possibility of making a perpetual motion machine, which could convert the vacuum energy into useful mechanical work. In addition, we find that the deviation of the temperature of the particle from its NESS temperature causes the particle to lose or gain internal energy in such a way that the particle would return to NESS after deviating from it. This enables experimental measurements of the NESS temperature of the particle to serve as a feasible signature for these quantum vacuum frictional effects.