Mathematical Physics comprises in part the work on Integrable Systems as well as in general the more mathematical aspects of physical systems, for example quantum systems. This may involve quantum field theoretical models or models in statistical mechanics. The Applied Analysis work in the department concentrates on multi-parameter spectral methods, linear and nonlinear special functions and associated quantum (integrable) systems both continuous as well as on the space-time lattice.

Current trends in microwave semiconductor technology take advantage of developments in low-dimensional structures using hetero-junctions. An example of this is the High Electron Mobility Transistor (HEMT) using Gallium Arsenide and Aluminium Gallium Arsenide in which electrons suffer little scattering. Manufacturers of these devices are constantly trying out different layer structures in order to improve performance, and require fast and accurate solutions of the modelling equations. We are looking at this HEMT problem and others in two main ways: testing the various assumptions behind the equations using relatively simple numerical codes, and developing new numerical codes for more efficient solutions.

The theory of integrable discrete systems also extends into the quantum domain, and it is here that the true richness of integrability is most visible (quantum mechanics being in essence a theory of discrete and algebraic objects). The current research concentrates on formulating a proper quantum theory for discrete mappings and integrable systems living on the space-time lattice. Exploiting the exactness of the models and integrable structures (R-matrices, quantum Lax pairs and determinants) the investigation is set to produce rigorous and analytic answers to questions which for other models are only accessible through numerical and perturbative methods. As such, quantum integrable discrete models form a paradigm for the development of new approaches in the quantum regime which have potential implications to areas such as string and conformal field theory, as well as in the theory of random matrices in mesoscopic physics, quantum computing and nanotechnology.

Understanding the underlying mechanisms of many nonlinear mathematical models arising in Physics, Biology and Medicine calls for the development and investigation of new analytical tools. For example many biological problems are modeled through reaction-diffusion systems of quasi-linear parabolic differential equations. Techniques based on the maximum principle and differential inequalities are being unified to provide tools with which to study qualitative behaviour of many biological and medical systems including morphogenesis, cell dynamics, as well as angiogenesis, vascularisation and metastasis of malignant tumours. In particular theorems have been obtained which can be used to establish the existence and stability of traveling wave solutions. This in turn has led to a novel numerical method for their calculation. Ideas drawn from a study of the theory of reinforced random walks is helping with the understanding of biological processes at the molecular and cellular level.