Quantum processes with memory: from open systems to many-body dynamics

ABSTRACT

Quantum systems are never perfectly isolated, and when the environment retains a memory of the system's past, the standard master equation description fails. There has recently been a shift in the theoretical characterization of such non-Markovian open quantum systems towards quantum process tensors, essentially a multi-time generalization of the traditional master equations. Originating in quantum information theory, process tensors provide a framework for systematically quantifying temporal correlations, or memory, in quantum dynamics. This makes it possible to treat open systems with methods developed for correlated many-body states. In particular, process tensors can be constructed systematically as temporal matrix product states, a numerical approach that has proven highly effective even for strongly correlated systems. In this talk I will give a general introduction to the field, connecting quantum process tensors with influence functionals and clarifying their relation to dynamical maps and many-body dynamics. I will then present results from my own research, including applications to quantum impurity models.

BIOGRAPHY

Valentin is a postdoctoral researcher at TU Berlin, where he joined André Eckardt's group in 2025 to study many-body dynamics in non-equilibrium systems. He completed his PhD in physics at TU Dresden in 2022 under the supervision of Walter Strunz, supported by a position funded by the Max Planck Institute for the Physics of Complex Systems. He then remained at TU Dresden as a postdoc until 2024, developing numerical methods for open quantum systems.