Our Independent Max Planck Research Group is located at the Max Planck Institute of Quantum Optics in Garching, Germany. Our research focus lies at the intersection of theoretical solid state and atomic physics. We are particularly interested in systems that feature a strong interplay of few- and many-body physics and aim to gain a deeper understanding of its significance for the dynamics, spectroscopic and transport properties of quantum matter realized in ultracold atomic gases and semiconducting materials.
In order to make progress in understanding complex quantum matter, it is important to identify systems which allow not only to study physics from different perspectives, but which also highlight universal aspects of the underlying dynamics. Discovering such universal connections can provide a basis to establish new phenomena that universally appear in artificial cold atomic quantum system and actual solid state materials with the potential of quantum technological applications.
In this spirit cold atomic quantum systems can serve as a platform for an applied quantum simulation of solid state materials and the goal to discover universal connections between both fields drives our research agenda. Remarkably, two-dimensional van-der Waals materials — with graphene being a famous example from this rapidly growing field of research — feature such a unique similarity to ultracold atomic quantum gases. Specifically, excitons interacting with electrons in two-dimensional semiconductor heterostructures realize Bose-Fermi mixtures that are closely related to those studied in ultracold atoms. Indeed, one example for the synergy of the two fields of van-der-Waals materials and ultracold atoms is the measurement of repulsive polarons in two-dimensional semiconductors  following our theoretical prediction [2,3] and their first observation in ultracold atoms [4,5], for a review on recent progress see  and . Building on our expertise at the intersection of solid state and atomic physics, our research group focusses on studying and exploiting such universal connections between solid state and cold atomic physics to theoretically discover novel states of quantum matter and finding ways to actually realize those in experiments.
In our theoretical pursuit of this goal we rely on a wide set of theoretical few- and many-body methods (including quantum field theory, diagrammatics, functional renormalization group, time-dependent variational wave functions, functional determinants, and exact approaches to few-body problems). We aim to both improve these methods as well as to develop new theoretical tools that allow to deepen our understanding of universal aspects of few- to many-body dynamics in quantum matter.
Our group has many active collaborations with theorists and experimentalists in the United States, Austria, Denmark, Switzerland and throughout Germany, and we also work in close connection with other groups within the research community in the Greater Munich area.
 M. Sidler et al., Nat. Phys. 13, 255 (2017).
 R. Schmidt, and T. Enss, Phys. Rev. A 83, 063620 (2011).
 R. Schmidt, T. Enss, V. Pietila, and E. Demler, Phys. Rev. A 85, 021602(R) (2012).
 C. Kohstall et al., Nature 485, 615 (2012).
 M. Koschorreck et al., Nature 485, 619 (2012).
 R. Schmidt, M. Knap, D. A. Ivanov, J.-S. You, M. Cetina and E. Demler, Rep. Prog. Phys. 81, 024401 (2018).
 M. Cetina, M. Jag, R. S. Lous, I. Fritsche, J. T. M. Walraven, R. Grimm, J. Levinsen, M. M. Parish, R. Schmidt, M. Knap, E. Demler, Science 354, 96 (2016).