Quantum phase transitions

Many fundamental and important physical phenomena emerge as a result of strong fluctuations above the ordered state of a physical system. Prominent among such phenomena are classical phase transitions driven by thermally induced fluctuations.

Furthermore, in this day and age many important technological applications involving nanoscale systems rely on low dimensionality, where fluctuations around ordered states are particularly important, even at zero temperature. Such zero-temperature fluctuations are called quantum fluctuations, and are controlled by parameters of a quantum mechanical Hamiltonian rather than temperature.

The study of strong quantum fluctuations and associated phase transitions between novel types of quantum condensates, are therefore of great current interest both from a fundamental physics point of view, but also from a technological point of view.  Systems where such physics is important involve low-dimensional quantum antiferromagnets, superconductors, low-dimensional strongly correlated systems with proximity-induced order (both in the particle-hole and particle-particle channel), and hybrid structures of the above.

In our group, we study novel paradigms for phase transitions within the realm of quantum phase transitions, investigating the possibility of going beyond the well-known paradigms established by the seminal works of Landau, Ginzburg, and Wilson, and which are inherently quantum mechanical. Of particular interest is the character of such novel and intriguing phase transitions involving competing order parameters and order parameters with several components, the critical fluctuations of these, and the interplay bertween them. Furthermore, the study of quantum transport in low-dimensional structures, and how quantum fluctuations and quantum criticality influence these, form a centrepiece of our research.

Quantum phase transitions

Wed, 02 Sep 2015 13:06:39 +0200