Systems composed of many microscopic particles exhibit a rich variety of collective phenomena, arising from the interplay of two principal ingredients: the quantum mechanical nature of the particles (primarily reflected by their wave-like character), and the interactions among them. These combined effects provide the mechanism for the formation of various distinct phases of matter and transitions between them, and to the emergence of elementary excitations (quasi-particles) which often possess very different properties than the original constituents. A prominent example of collective behavior in quantum matter is manifested by the electrons in solids, in terms of measurable properties such as conduction phenomena, magnetism and optical properties. Particularly intriguing behavior emerges in electronic systems at low temperatures, and when at least one of the dimensions is reduced (namely, thin films, quantum wires and quantum dots). Under such conditions, both quantum effects and the role of interactions are typically enhanced. Theoretical research in condensed matter physics is designed to provide the understanding of this wealth of phenomena, implementing advanced methods of statistical mechanics and quantum field theory and a variety of computational techniques.
The condensed matter theory group in the department expertizes on a number of topics at the frontier of this field:
- Superconductivity: unconventional and high-temperature superconductors, vortex dynamics and phases of vortex matter, quantum fluctuations in low-dimensional superconductors and the superconductor-insulator transition.
- Electron transport in disordered media: localization, metal-insulator transition and quantum chaos.
- Transport phenomena in low-dimensional and strongly correlated electron systems: quantum wires and quantum dots, low-dimensional quantum spin systems, graphene, quantum Hall systems and topological insulators.
- Magnetism: magnetic impurities and the Kondo effect, magnetic ordering in reduced dimensions, quantum magnetism and spin liquids.