Area A: Foundations of Quantum Science

Summary

The emergence of the classical world from quantum many-body dynamics is the unifying theme of this research area and connects the four disciplines of IQ^ST. Indeed, the quantum-classical transition and the survival of coherence properties can be studied in many situations in physics and chemistry. Controlled coupled spin systems as realized by strongly interacting Rydberg atoms, coupled nitrogen-vacancy (NV) centers in diamond, or an array of molecular nanomagnets and magnetic nanoparticles represent a few examples from physics and physical chemistry. Photosynthetic complexes of bacteria, marine algae and higher plants as well as polymer chains are examples from biology and chemistry. Indeed, recent experiments have provided direct evidence for quantum coherence in the excitation energy transport within such many-body systems.

The full characterization and the preparation of some quantum states corresponding to a many-body system require an exponentially large number of resources. For this reason the simulation of such a quantum system on a classical computer implies that we are restricted to a small number of particles. Indeed, traditional numerical methods fail in the simulation of fermionic systems which are realized in strongly correlated metals, or in cold atom clouds with repulsive interactions and which represent a central topic of the research area Complex Quantum Systems. It is this exponential scaling of complexity that also limits the predictability of possible phases or phase transitions. Indeed, improved methods, which rely on recent developments in classical and quantum information science, might extend current capabilities of simulating exotic quantum states such as spin-liquids or topological states in frustrated quantum magnets pursued experimentally in Tailored Quantum States.

Throughout Foundations of Quantum Science we profit from quantum information science which for example, has developed tools for quantum state tomography using limited resources and efficient state preparation using mathematical optimal control and reduced model techniques. Indeed, Reduced Basis Methods form a timely and active field of research in numerical mathematics and information theory. The main goal is the representation, simulation, and optimization of a highly complex system by one with a very small number of degrees of freedom in real-time. Quantitative measures for the errors caused both by the reduced modeling and the numerical simulation need to be developed. In combination with ab-initio calculations and the derivation of effective models from a microscopic description of quantum systems, this line of research of Foundations of Quantum Science forms the basis of a simulation-driven design of correlated quantum matter using ultra-cold atoms or man-made heterostructures as proposed in Complex Quantum Systems.

Research themes

Novel quantum systems to investigate the quantum-to-classical transition
Simulation of far-from-equilibrium phenomena in large scale correlated quantum systems
Mathematical modeling, simulation, and optimization of quantum many-body systems
Coherence effects in biological and chemical systems and catalytic processes
Ab-initio derivation of effective models from microscopic theory

People

Prof. Dr. Wolfgang Arendt, Institute for Applied Analysis, Ulm University

Prof. Dr. Martin Bossert, Institute of Telecomunications and Applied Information Theory, Ulm University

Prof. Dr. Hans Peter Büchler, Institut für Theoretische Physik III, Universität Stuttgart

Prof. Dr. Tommaso Calarco, Institut für Quanteninformationsverarbeitung, Universität Ulm

Prof. Dr. Axel Groß, Institute for Theoretical Chemistry, Ulm University

Prof. Dr. Susana Huelga, Institut für Theoretische Physik, Universität Ulm

PD Dr. Timo Jacob, Institute for Electrochemistry, Ulm University

Dr. Elena Mena-Osteritz, Institute of Organic Chemistry II ans Advanced Materials, Ulm University

Prof. Dr. Alejandro Muramatsu, Institut für Theoretische Physik III, Universität Stuttgart

Prof. Dr. Martin B. Plenio, Institut für Theoretische Physik, Universität Ulm

Prof. Dr. Wolfgang P. Schleich, Institut für Quantenphysik, Universität Ulm

Prof. Dr. Joris van Slageren, Institut für Physikalische Chemie, Universität Stuttgart

Prof. Dr. Karsten Urban, Institute for Numerical Mathematics, Ulm University

Prof. Dr. Jörg Wrachtrup, 3. Physikalisches Institut, Universität Stuttgart

Prof. Dr. Wojciech Zurek, Los Alamos National Laboratory