Strongly correlated Quantum Fields out of equilibrium

Describing interacting many body quantum systems which exhibit strong correlations is among the hardest problems in physics. This is especially true for out of equilibrium dynamics and relaxation. Such Systems appear in a very broad context ranging from cosmology through high-energy physics to condensed matter and biology. A full description very quickly goes far beyond what can be calculated on classical computers. Often, such systems and their observable physics are described by Quantum Field Theories (QuFTs). Building model systems in the laboratory will allow to quantum simulate th ese systems and their physics and test theoretical models and their approximations. In the project SCQS-oE we will build a quantum simulator for strongly correlated quantum systems and experimentally study their equilibrium properties and non-equilibrium evolution and relaxation over a wide range of parameters and physical settings. The starting point of our investigations is a quantum simulation of the Sine -Gordon model via two tunnel-coupled 1D superfluids. In the experiments we can tune the physics form simple gaussian to very strongly correlated. We will focus on 4 main objective s: (i) Relaxation after a quench (rapid change of parameters). (ii)Dynamical driving to: (a) prepare the SG QuFT close to its quantum vacuum state and (b) build a model of an expanding universe. (iii) Strong excitations and particle creation: We will create starting conditions which can be outside the validity of the SG model and thereby study the range of validity of the quantum simulator. (iv) Non-equilibrium dynamics in spatially inhomogeneous systems, for example the boundary SG model. Central to all these investigations will be to verify the model and to probe its range of validity. Experiments will be conducted on an AtomChip with a one-dimensional (1D) quantum gas of Rb atoms. The 1D systems will be individually probed (1) in situ through the evolution of density and momentum (rapidity); and (2) by measuring interference and correlations, to observe how the many-body system and its macroscopic wavefunction evolves. Splitting a single 1D system into double well potentials allow us to create the two tunnel- coupled 1D superfluids which constitute the quantum simulator of the SG model, and precisely control the strength of its correlations. Moreover, matter wave interference gives us direct access to the simulated quantum field and its coherence. Extracting quantum correlations gives detailed insight into the many body phases and their field theory description.