Speaker
Emanuel Gull
(University of Warsaw & University of Michigan)
Description
Response functions are fundamental objects in quantum many-body theory. For equilibrium and steady-state systems, retarded response functions are analytic in the upper half of the complex plane, and their imaginary part has a definite sign. These analytic properties enable compact and systematically improvable representations based on pole approximants and moment theory, allowing high-precision calculations while significantly reducing computational complexity. This talk will provide an overview of the underlying analytic structure, introduce controlled approximation schemes, and discuss their application to the efficient computation of response functions.
Author
Emanuel Gull
(University of Warsaw & University of Michigan)