Ph.D Thesis


Ph.D StudentIsrael Klich
SubjectQuantum Fields under the Influence of External Conditions
DepartmentDepartment of Physics
Supervisor Full Professors Mann Ady


Abstract

One of the manifestations of Quantum Field Theory in macroscopic physics is the Casimir effect. In this effect boundary conditions modify the ground state energy of the electromagnetic field and result in a force.

In the first part of this work, we study the electromagnetic Green's function and the Casimir energy of a medium with non-homogenous permeability. As an application we consider the case of a dielectric - diamagnetic ball, with a core made from a different material. Depending on the parameters, the forces on the inner and outer interfaces can be either inward or outward. Finally we calculate the interaction between two slabs of materials with arbitrary permittivity and permeability. We show that the force may be either attractive or repulsive, contrary to the non-magnetic case where the force is attractive. This effect, if realized, may be of fundamental interest in mesoscopic physics and nanomechanical applications.

The second part of the work is devoted to fermion fields. We start by studying the statistics of charge transport between materials coupled through a time dependent scatterer. The full counting statistics was first studied by Levitov et al, and can be expressed in terms of a determinant of a single particle operator. It is used to study the quantum effects governing noise in mesoscopic circuits. Implementing a relation between Fock space traces and single particle determinants, we present a novel derivation and generalizations of Levitov’s formula. Finally, we demonstrate that given a partition of a single particle Hilbert space into orthogonal subspaces, the ground state of quasi-free fermions may be factored into pairs of entangled modes. We derive expressions for the entanglement entropy and for particle number fluctuations, and relate these by a lower bound on the entropy.