Quantum theory of light and dispersion forces in non-reciprocal and bianisotropic media

Abstract

In this thesis the quantum theory of light in absorbing media, macroscopic quantum electrodynamics, is extended to describe the quantised electromagnetic field in general linear absorbing media. The CasimirPolder potential between a particle and examples of bianisotropic media are presented. The electromagnetic properties of a general linear medium that may possess a spatially non-local and even non-reciprocal response are fully described by a complex conductivity tensor. The quantisation of the electromagnetic field in general media was achieved through enforcing a commutation relation between Langevin noise current operators whose presence also ensure compliance with the fluctuation dissipation theorem. The quantisation of the electromagnetic field in media characterised by bianisotropic response functions is shown. The duality invariance of an electromagnetic system was found to be a continuous symmetry in general and a discrete symmetry when the medium has a reciprocal response. The chiral component of the Casimir-Polder potential was derived in the weak coupling regime. It was found to be either attractive or to repel chiral molecules, depending on the chiral identity of the objects. The molecule and the medium must both possess chiral features otherwise the chiral contribution to the Casimir-Polder potential does not exist. By constructing a cavity between media of opposite chirality, enantiomer separation can occur when particles are initially in an excited state and the resonant frequency of the media is equal to the relevant transition frequency of the molecule. The quantisation of the electromagnetic field in moving media was achieved on the observation that a locally responding isotropic dielectric in motion is equivalent to a non-reciprocal linear bianisotropic medium from the perspective of a moving frame. A generalised reciprocity condition that constrains the Green’s function of the electromagnetic field in moving media was derived.