Flavor superconductivity and superfluidity

Abstract

In these lecture notes we derive a generic holographic string theory realization of a p-wave superconductor/superfluid. For this purpose we also review basic D-brane physics, gauge/gravity methods at finite temperature, key concepts of superconductivity and recent progress in distinct realizations of holographic superconductors and superfluids. The gravity dual is a D3/D7-brane construction yielding a superconducting or superfluid vector-condensate. The corresponding gauge theory is 3 + 1-dimensional N=2 supersymmetric Yang-Mills theory with SU(Nc) color SU(2) and flavor symmetry. It shows a second order phase transition to a phase in which a U(1) subgroup of the SU(2) symmetry is spontaneously broken and typical superconductivity signatures emerge. For example an infinite dc conductivity, a conductivity (pseudo-)gap and the Meissner-Ochsenfeld effect are found. Condensates of this nature are comparable to those recently found experimentally in p-wave superconductors such as a ruthenate compound. A string picture of the pairing mechanism and condensation is given using the exact knowledge of the corresponding field theory degrees of freedom. © 2011 Springer-Verlag Berlin Heidelberg.