# Quantum Criticality, High Tc Superconductivity and the AdS/CFT Correspondence of String Theory

## Professor Jan Zaanen, University of Leiden

**Date:**
January 19, 2011
10:30

**Place:** Seminarraum 348 / 349, Fakultät für Physik der LMU München, Theresienstr. 37, 80333 München

The central mystery in quantum matter is the general nature of matter
formed from fermions. The methods of many body quantum
physics fail and one can only rely on the phenomenological Fermiliquid
and BCS theories. However, in heavy fermion systems and
cuprates one deals with non Fermi-liquid quantum critical metals,
and to understand the superconductivity one needs to understand
these normal states first. Remarkably, it might well be that the
mathematics of string theory is capable of describing such states
of fermion matter. The AdS/CFT correspondence translates this
problem into an equivalent general-relativity problem involving the
propagation of classical fields in an Anti-de-Sitter space-time with a
black hole in its center. This development started with the demonstration
that AdS/CFT predicts correctly the low viscosity of the
quark-gluon plasma of the Brookhaven heavy ion collider. In 2007 it
was realized that it could have relevance to high Tc superconductors
but only last year the focus shifted to the way AdS/CFT processes
fermions, creating much excitement: it appears that both emergent
heavy Fermi-liquids and non Fermi-liquids can be gravitationally
encoded, as well as holographic superconductors having suggestive
traits in common with the real life high Tc variety.