Diagrammatic Monte Carlo simulation of quantum impurity models
Prof. Dr. Philipp Werner (ETH Zürich)

Quantum impurity models play an important role as representations of molecular conductors and in the ``dynamical mean field" method, currently one of the most promising tools for studying the physics of fermionic lattice models. Despite their zero-dimensional nature, the numerical simulation of impurity models remains a challenging task. Progress has been achieved with the recent development of diagrammatic Monte Carlo techniques. This simulation approach relies on a diagrammatic expansion of the partition function and the stochastic sampling of collections of diagrams. I will explain the key ideas for the diagrammatic method and illustrate its power and flexibility with dynamical mean field results for single-band and multi-orbital models. I will also discuss the adaptation of the diagrammatic Monte Carlo technique to real-time dynamics in non-equilibirum systems.