ICTP - The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy

CM Research Profile
Strongly Correlated Systems

Strongly Correlated Systems

We are pursuing, in conjunction with the SISSA group, several research projects concerning strongly correlated quantum systems, using both analytic and numerical techniques. The current research topics include:

1. Model studies for superconductors and insulators (Michele Fabrizio, Subodh Shenoy, Erio Tosatti, YU Lu)

Various models for High-Tc and molecular superconductors, and Mott insulators, including U(1) xSU(2) Chern-Simons gauge field theory, implications of orbital degeneracy, dynamical Jahn-Teller effect and interplay of lattice distortions with electron correlations, etc., have been considered.

2. Low-dimensional quantum spin systems ( Michele Fabrizio, Alexander Nersesyan, YU Lu)

The symmetry analysis, analytic and numerical techniques (including bosonization, conformal field theory and density matrix renormalization group) have been used to study the energy spectrum and physical properties of these spin systems (chains, ladders, spin-Peierls systems, etc.). Effects of frustrations, impurities and disorders have also been examined.

3.Quantum impurity problems ( Michele Fabrizio, Alexander Nersesyan, YU Lu)

This is an "old" problem in quantum many body physics, with a number of outstanding issues. Several attempts have been made to explore the Fermi-liquid versus non-Fermi-liquid behaviour in the single impurity models. Numerical and analytical arguments have been used to resolve the controversy regarding the orthogonality catastrophe issue in Luttinger liquids.

4. Quantum liquids, solids and gases ( Stefano Fantoni, Subodh Shenoy)

In close collaboration with SISSA, we study the structure and dynamical properties of quantum fluids using ab initio calculations, based on a microscopic description of the system given by the bare hamiltonian. The fundamental perspective of these studies is to bridge the gap between heuristic or phenomenological treatments with calculations, based on first principles. We study quantum coherence effects on macroscopic scale in superfluid systems, including trapped Bose-Einstein condensates and 3He-B. In particular, we consider: non-linear Josephson oscillations, collapses and revivals of macroscopic coherence, damping of collective modes at zero-temperature, symmetry breaking in finite systems, etc.

5. Other strong correlation models (Erio Tosatti)

In collaboration with SISSA, various strong correlation models have been explored to study traditionally "non-strong-correlation" problems, like the surface disordering transitions (as quantum 1D problems). We also study quantum paraelectricity in perovskites.