Fluctuation-induced phenomena in non-equilibrium systems

Abstract

In this thesis, we investigate the implications of fluctuations in systems away, possibly even far, from equilibrium due to their motion either in or out of thermal equilibrium. This subject encompasses several topics in physics including the dynamical Casimir effect in the presence of moving boundaries, and non-contact friction between objects in relative motion. In both cases, photons are created due to the coupling of the motion and zero-point fluctuations in the vacuum, resulting in dissipation and radiative loss. We introduce a general formalism, equally applicable to lossy and ideal objects, to compute the quantum radiation and dissipation effects solely in terms of the classical scattering matrices. We obtain trace formulas which are general and independent of any approximation scheme where numerous examples, many novel, are discussed in great detail. Specifically, we give an exact treatment of quantum fluctuations in the context of a neutral rotating object, and show that it spontaneously emits photons and drags objects nearby, and compute the associated photon statistics and entropy generation. In the context of non-contact friction, we find a quantum analog of the classical Cherenkov effect for two neutral plates in relative motion, purely due to quantum fluctuations. We present a number of arguments and exact proofs, including a method introduced in the context of quantum field theory in curved space, as well as the scattering approach, to show that a friction force between two plates appears at a threshold velocity set by the speed of light in their medium.