Current projects

Strongly correlated electron models for organic superconductors.

These materials have many properties similar to high-temperature superconductors, including competition between insulating, quantum antiferromagnetic, superconducting, and exotic metallic phases. Given a model Hamiltonian which includes the interactions between the electrons the challenge is to calculate the properties of its ground state and excited states and compare to the rich phase diagrams observed experimentally.

Quantum phase transitions in random systems.

Most phase transitions in nature are driven by thermal fluctuations; examples include ice melting or heating a ferromagnet into a paramagnet. Quantum phase transitions occur at zero temperature and are driven by quantum fluctuations. They are important to understanding properties of many strongly correlated electronic materials. Such transitions can persist in the presence of disorder due to impurities but they exhibit an even richer physics. For example, ensemble averages are dominated by rare configurations. Due to the theoretical complexity of this problem the focus in on studying the simplest possible model Hamiltonians which exhibit the relevant physics and not making approximations.

Mesoscopic electronic devices.

Future computer technology will make use of ultrasmall electronic devices such as quantum dots and single electron transistors whose properties are dominated by quantum effects. In the presence of disorder large statistical fluctuations in the electrical resistance are observed. The associated theory has a rich mathematical structure and is being investigated with members of the UQ Centre for Mathematical Physics.

Electronic transport in DNA.

Recent experiments have shown that electrons can travel large distances along the double helix of DNA without losing the coherence of their wavefunction. Model Hamiltonians for this process, which take into account the base pair sequence and the interaction with the environment are being investigated.