Seminarium Optyczne

How does a quantum many-body system reach thermal equilibrium after a quench? And how are theequilibrium properties related to the microscopic parameters of the system? While it is generally difficult toaddress this question using classical numerical methods, quantum simulators can provide alternative ways, whichmay further facilitate the development of new effective theoretical descriptions. Quantum gas microscopy inparticular offers unique insights into thermalization dynamics via access to correlation functions and fullcounting statistics. We use a new Cesium quantum gas microscope with small lattice spacing to explore therelaxation dynamics of large quasi-one-dimensional bosonic quantum many-body systems. In particular, weprepare ladder systems with a length of up to 40 sites at half filling and tunable coupling between the legs. Thisallows us to study the crossover between integrable and chaotic dynamics. Using an unsupervised machine-learning algorithm we reconstruct the site-resolved density distribution with high fidelity and study the dynamicsvia local densities, density-density correlation functions and particle number fluctuations. While the local meandensity relaxes within few tunneling times, we find that global equilibrium is reached on much slower timescales.The scaling of the equilibration time as a function of subsystem size provides an indication of the intrinsictransport dynamics enabling us to investigate the crossover from ballistic to diffusive dynamics as the couplingbetween the legs of the ladder is increased.