Non-equilibrium systems are found everywhere in nature. Even though much is known about equilibrium properties, the pathways of relaxation and their relevant time scales are much less understood.
Many-body quantum systems out of equilibrium and their dynamics and relaxation are central to many different areas of physics. Open problems appear at vastly different energy and length scales, ranging from high-energy physics and cosmology to electron dynamics in condensed matter and the emerging field of quantum biology. Moreover de-coherence and the emergence of the classical world from the microscopic quantum description is an inherent non-equilibrium process.
In this project we propose to probe the fundamental physics governing the non-equilibrium evolution and relaxation in quantum many-body systems through laboratory experiments. Systems of ultra-cold atoms provide unique opportunities for studying non-equilibrium problems and their related quantum dynamics. A large variety of tools allow precise preparation of far-from-equilibrium initial states and coherent quantum evolution can be observed on experimentally accessible timescales. In addition, the tunability in interaction, temperature and dimensionality allows the realization of a multitude of different physical situations, giving insight into the corresponding quantum field theories.
Through building specific model systems we will study a wide variety of non-equilibrium quantum dynamics under conditions ranging from weakly interacting to strongly correlated, from weakly disturbed to quantum turbulent, from slowly progressing to unstable and exponentially growing. We expect to get deep insight into such intriguing phenomena as pre-thermlization, (quasi)particle creation, amplification of excitations and entanglement spreading.
A central part in our investigations is played by isolated systems, where the relaxation is entirely due to internal quantum dynamics. This will, in addition to the more general questions above, allow to probe directly if, and under which circumstances, classical physics can emerge from microscopic quantum evolution through the dynamics of complex many-body systems.
Our ultimate goal is insight into: What does it take for a many-body quantum system to relax to an (apparent) equilibrium state? Which universal properties and scaling laws govern its evolution? We hope to pave the way for a general, even universal, understanding of non-equilibrium many-body quantum systems across the plethora of research fields for which they are important.
