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.
The word "quantum system" refers to any physical system in which manifestations of quantum mechanics are apparent. Such manifestations are, e.g., quantization of energy or other observables, interference of matter waves, nonlocality, or tunneling. These manifestations distinguish quantum mechanics from classical mechanics, where observables are continuous, particles do not interfere, and tunneling is prohibited. Quantum systems include the entire microscopic world, such as elementary particles and atoms, but also nanoscale electric conductors, semiconductors, large molecules, or certain materials whose macro-scale properties are determined by micro-scale quantum mechanical interactions.
The concept of "complexity" describes the situation in which a system's behavior can not be traced to its microscopic constituents. Complex systems must be described in terms of emergent properties that are characteristic of the many-particle system. This is a concept that is relevant both in the classical world (e.g., turbulence) and in quantum mechanical systems. Complex systems frequently have a large number of degrees of freedom, and they more often than not require statistical methods to analyze their behavior.
Upon combining these two concepts, complex quantum systems are then understood to be physical systems consisting of many particles, whose behavior is governed by quantum mechanical laws. This field includes many interesting and important research directions in contemporary theoretical physics, such as quantum transport, nanomagnetism, mesoscopic superconductivity, quantum chaos, electronic systems with strong correlations, complex materials, certain areas of biophysics, cold atomic gases, and quantum measurement, quantum computation, or quantum information.