# Theory

The laws of quantum mechanics govern not only the behavior of elementary particles, but also the collective properties of many-body systems at low temperatures. Understanding the various phases in which quantum matter can organize itself has been a long-standing goal of theoretical physics, motivated both by the quest for new materials and by fundamental questions about the emergence of exotic phenomena in strongly correlated systems.

In parallel to that, the last two decades have seen the establishment of quantum information science, a highly inter-disciplinary field with the basic aim of harnessing quantum effects to enhance the processing of information in a diversity of scenarios. Moreover, quantum information has established a new perspective and set of tools, which have brought a deeper understanding and dozens of new results and insights to the understanding of quantum theory itself.

Our group at the International Institute of Physics (IIP) is interested in several research lines under the quantum information and quantum matter umbrella, including topics such as: the interface between quantum information and many-body physics, quantum foundations, quantum enhanced protocols, quantum phase transitions, analytical methods of quantum field theory to study strongly correlated systems, quantum magnetism in low dimensions, quantum causality and experimental implementations.

We theoretically study non-equilibrium dynamics of complex quantum systems, focussing on ultra cold gases near 0K temperature, highly excited Rydberg atoms, opto-mechanical devices and hybrid assemblies of these.

Experimentalists can now assemble rather simple building blocks such as atoms, molecules or gas-clouds into ever more complex quantum systems with detailed control. We thus follow nature’s path of creating immense complexity, such as life, out of rather simple ingredients. Re-creating complex systems from nature under well controlled conditions in the laboratory out of e.g. cold atoms is called quantum simulations. This is an idea by Richard Feynman, with which scientists hope to understand systems that are too hard to simulate on our computers, or to get some new ideas that emerge due to the (typically) a lot simpler conditions in the laboratory system.

Our group is interested in discovering ways how the tools above can be turned into quantum simulators for energy transport (e.g. in photosynthesis), or concepts from quantum chemistry (e.g. conical intersections). Beyond that we are also interested in quantum mechanics on mesoscopic scales and numerical solutions of the many-body quantum problem.