Dualities between quantum field theory and gravity
The group establishes and investigates generalisations of the AdS/CFT correspondence - so-called gauge-gravity theory dualities. One focus is on gravitationally dual descriptions of gauge theories similar to the theory of quantum chromodynamics, which describes the strong interaction in the Standard Model of elementary particle physics. Another, particularly current focus is the better understanding of quantum-critical phases in solid-state physics, such as those that occur in heavy-electron systems or in high-temperature superconductors, with the help of the AdS/CFT correspondence. These phases are characterised by the absence of well-defined quasiparticle excitations and by thermoelectric transport deviating from the Landau theory of Fermi liquids. These properties are described by the AdS/CFT correspondence at finite temperature and density, so that the study of black holes in the AdS/CFT duality leads to new universal insights into the physics of strongly correlated matter. First results exist, for example, on superfluids and superconductors, on electric transport in disordered strongly correlated systems, and on hydrodynamic transport and viscosity.
These results are also relevant in the description of the quark-gluon plasma, a new state of strongly coupled matter at finite temperature and density, which played an important role in the evolution of the early universe after the Big Bang. In addition, the group studies time-dependent processes, non-equilibrium dynamics, thermalisation and novel connections between quantum information theory and black hole theory using the generalised AdS/CFT correspondence.