Novel excitations in driven vortex channels in a superconductor, and solitary waves of light and atoms in photonic crystal fibres

[摘要] This is a thesis in two parts. In Part I, we will study the shear response of confined vortices. In Part 2, we will study light and matter interactions in photonic crystal fibres. Whilst the approaches of each are completely different, they both have the same central theme: solitons. In the first part of this thesis we study the static and dynamic properties of vortices within a Type-II superconductor, confined within a channel. The channel comprises a collection of pinned vortices, which form the perfect triangular lattice in the boundary, and rows of “free” particles which are driven via an external force. We provide two main results within this system. First we calculate the potential stemming from the boundary, and derive (under certain approximations) the phenomenologically accepted result for the critical shear dependence on the system width. We then study a novel system in which a defect is placed in a deformable potential; specifically a system comprised of two channels where one or both channels have a defect. This system provides a mechanism for the proliferation of kink/kink and anti-kink/anti-kink pairs as the defect binds to a local excitation in the form of a “breather”. We observe and explain what appears to be an action at a distance style interaction between excitations. In Part II, we will utilise the nonlinear effects of a Bose condensate and the unique optical properties of a photonic crystal fibre to demonstrate there are nonlinearly stable configurations which exist in the vicinity of an optical mode with a cut-off. These are solitary waves, whose relative composition of atoms and photons may be changed via altering the detuning of light from an atomic transition and Feshbach resonances.

[发布机构] University:University of Birmingham;Department:School of Physics and Astronomy

[关键词] Q Science;QC Physics