Special Colloquium

Title: Quantum phase transitions in spin systems and ultracold gases

Speaker: Sebastian Egger, Professor, Technische Universität Kaiserslautern

Location: Room 111, Physics Building

Time: 15:00-16:00, Thu, Oct 9, 2014

Abstract:

Quantum phase transitions (QPT) have been of broad interest in quite different materials including heavy fermion compounds, unconventional superconductors, and Mott insulators.  Recent experiments on coupled spin systems and ultracold atoms allow the systematic study of quantum criticality which will be reviewed in this talk. Further numerical simulations show that the detailed analysis of the critical behavior allows a deeper insight into the underlying coupling arrangement in magnetic materials.  In the second part of the talk the role of frustration and impurities on the critical behavior is discussed.  Due to the residual large entropy at low temperatures frustrated models often display rich quantum phase diagrams, including topological phases, supersolids, or spin liquids. At the same time impurities and boundaries may lift the degeneracy and thereby significantly change the physical behavior, which is discussed for several different examples.

Biography:
1. Professional Career
1986 - 1988 Studies of physics, Univ. Oldenburg. Vordiplom
1988 - 1990 Studies of physics, University of Wyoming, USA. Master of Science
1990 - 1994 Doctoral Student, Department of Physics, University of British Columbia, Vancouver, Canada, in the group of Prof. Dr. I. Affleck. Ph.D.
1994 - 1996 Postdoc Fellowship, Institute of Theoretical Physics, Chalmers University of Technology, Sweden, in the group of Prof. Dr. S. Östlund
1996 - 1997 Assistant Professor, Universität Göteborg, Sweden
1998 - 2004 Associate Professor, Chalmers University of Technology, Sweden. Fellow of the Swedish Research Council.
1999 Dozent, (Habilitation) Chalmers University of Technology.
Since June 2004 C4-Professorship at Fachbereich Physik, TU Kaiserslautern
2. Professional Duties/Stipends/Awards
Since 2010 Head of the Committee for quality in teaching (“Fachausschuss für Studium und Lehre”), Physics Department, Kaiserslautern.
Since 2010 Member of the University Steering Committee for Teaching, Kaiserslautern.
Since 2007 Head of the integrated graduate school of the DFG research center Transregio 49
2007 Suggested for the “Teaching Award Rheinland-Pfalz 2007“ by the Department of
Physics, TU Kaiserslautern
1998 - 2003 Special Research Fellow of the Swedish Research Council
1992 - 1994 University Graduate Fellow (UGF), Univ. of British Columbia, Canada
3. Research Areas
Theory of condensed matter and many body systems. Theoretical condensed matter physics in the area of strongly correlated electrons in reduced dimensions, especially magnetic insulators (spin chains, ladders, frustrated lattices), Luttinger liquids, quasi-one dimensional nanowires, carbon nanotubes, ultracold atomic gases.