Melissa Will, Technical University of Munich

Hilbert Space Fragmentation and Hybrid Hydrodynamics in a Bose Hubbard Model

Quantum many-body systems out of equilibrium can exhibit very rich and exciting phenomena. A particularly relevant question is whether and how a quantum system thermalizes under its own unitary evolution. In this context, three classes of systems can be distinguished: ergodic, localized and intermediate regimes exhibiting quantum many-body scars. We consider a Bose Hubbard model on a square lattice in presence of a tilted field and demonstrate perturbatively the emergence of Hilbert space fragmentation (HSF) when fine tuning the on-site interactions. We investigate the quench dynamics of this system and find that the relaxation dynamics strongly depends on the chosen initial state—which we interpret as a signature of HSF. Furthermore, we identify point like excitations on top of certain frozen states, for which we analyze their dynamics using a cellular automaton.