Dahlem Center for Complex Quantum Systems at Department of Physics, Freie Universität Berlin

© GettyImages/Erik Isakson

The Dahlem Center for Complex Quantum Systems is intended to provide an exciting forum to exchange ideas and stimulate collaboration between junior and senior scientists from Germany and all over the world. The center’s focus is on theoretical quantum condensed matter physics in the broadest sense. Home of the Dahlem Center is the Physics Department at Freie Universität Berlin. The Dahlem Center is an international center, open to researchers via short-term and long-term visiting positions, prestigious postdoctoral fellowships, and conferences.

There are 3 interesting research groups under this center.

AG Eisert- Quantum many-body theory, quantum information theory, and quantum optics

This leading group is concerned with research in quantum information theory, condensed matter theory and the intersection between the fields.

  • They ask what information processing tasks are possible using single quantum systems as carriers of information. They think about the mathematical-theoretical foundations of quantum information, specifically about the theory of entanglement and questions of tomography, but also about ways of realizing topological quantum computing.
  • A main emphasis of their theoretical research is in condensed matter theory, concerning static properties of quantum many-body systems, their efficient numerical simulation, as well as their quantum dynamics in non-equilibrium. Methods of tensor networks play a special role here.
  • They are also involved in identifying quantum optical realizations of such ideas, specifically using light modes or cold atoms in optical lattices.

Characteristic for the work is to be guided by the rigor of mathematical physics, but at the same time to be deeply pragmatically and physically motivated, which often leads to collaborations with experimentalists.


AG Metelmann-Emmy Noether Research Group-Theory of Engineered Quantum Systems

Their research focuses on the theory of engineered quantum systems. Among other things, this group deal with novel concepts on how to realize nonreciprocal (unidirectional) systems; they explore their fundamental properties and investigate their potential for real-world applications.


AG Brouwer-Prof. Dr. Piet Brouwer - Theoretical mesoscopic physics-Dahlem Center for Complex Quantum Systems (DCCQS)

Research areas
Theoretical mesoscopic physics; physics of disordered electron systems; quantum chaos; random-matrix theory; nanomagnetism

Current research
His research interests are in the field of theoretical mesocopic physics. Mesoscopic physics is a subfield of condensed matter physics that deals with the properties of small, mostly electronic systems, which are governed by the interplay of quantum mechanics and scattering by impurities or boundaries. Examples of such systems are semiconductor or metal wires, metal nanoparticles, carbon nanotubes, or semiconductor quantum dots. Similar physics also occurs for systems with multiple scattering of microwaves or light.

Questions of recent interest have been: What is the effect of Coulomb interactions in a quantum dot (a small metallic particle coupled to the outside world via point contacts) if the coupling between the quantum dot and source and drain electrodes is strong? What is the size-dependence of quantum-interference corrections to transport through quantum dots if the electron motion inside the quantum dot is ballistic? How does scattering off charged impurities affect the conductivity of graphene (a single sheet of carbon atoms as they occur in graphite)? How does the proximity to a superconductor affect the electronic properties of a ferromagnet?

Another topic of interest is magnetism on the nanoscale. His research addresses the effects of the spin-transfer torque, as well as consequences of quantum phase coherence and impurity scattering in nm-sized magnets.