## Research in Theoretical Physics

The Theoretical Physics Research Group at the University of Birmingham is primarily concerned with the understanding of condensed matter, ultracold quantum gasses and nonlinear-optics. Our approach to these problems is varied: We often use techniques from quantum field theory - the mathematics of particle physics. We develop phenomenological theories inspired by experiments. We develop simplified models more amenable to solution to capture the essential physics we are studying. We use numerical and computational techniques. In short, we adapt a wide range to techniques adapted to the problems in hand. There is considerable expertise in the group and a sense of collaboration which shares that expertise around. The broad areas of research interest include:

### Correlated Electron Systems

Solving problems involving interacting problems is notorious difficult. It also leads to some of the most fascinating phenomena and outstanding problems in condensed matter physics. The fact that electrons are quantum mechanical, strongly repel each other and coexist in a vaste range of different materials leads to the emergence of new phases of matter like electron nematics and surprises in old phases from superconductivity and magnetism. Our research interests include quantum magnetism, quantum criticality and non-Fermi liquids, the emergence of new types of order and understanding high temperature superconductors.

### Ultra-Cold Atoms

In the past ten years a new field of physics has emerged due to the ability to cool atoms down to billionths of a degree above absolute zero. The resulting quantum gas is a new type of correlated system but offers a degree of control and variety that has not been possible in electron fluids or liquid helium. The Birmingham theory group is a leader in this field, particularly in the area of rotating Bose condensates.

### Disorder and Mesoscopics

In the quest for miniturization we are reaching regimes where electronic devices approach atomic dimensions. How matter behaves in this domain is often surprising because it is dominated by quantum mechanics and the variability of the arrangement of atoms. Understanding the consequences of this is both of fundamental theoretical interest, and of technological significance particularly in the area of quantum computing.

### Information Theory and Optics

Our research is concerned with the boundaries and limitations of moving information through networks and fibres. While this is of practical significance in the internet age, the issues are deep at a fundamental level and concern disorder, non-linear effects including solitons and have much overlap with the other topics studied in the research group.

We offer PhDs in these areas and more.