Floating point precision imaginary time response functions in quantum many-body physics

The dynamics of quantum many-body systems in thermal equilibrium is amenable to the imaginary time formalism. The sequent numerical treatment of imaginary time propagators is central to many forms of perturbative and non-perturbative algorithmic approaches, e.g. perturbation theory, diagrammatic Monte Carlo, embedding methods like dynamical mean-field theory, etc. However, the prevailing techniques for numerical representation and computations in imaginary time, based on equidistant grids, are suffering from poor accuracy and poor scaling at low temperature. This talk will give an overview of the recent progress in numerical representation and computation using highly accurate and compact imaginary time representations, as well as an outlook for applications to real-time Green's functions.