The thermalization of an isolated quantum system can fail in the presence of quenched disorder, even with interactions. This phenomenon, known as many-body localization (MBL), has been recently the focus of much theoretical work, though many open questions still remain regarding its existence in higher dimensions or its robustness to a finite bath coupling. Ultracold atoms in optical lattices have emerged as an extremely suitable platform for the study of MBL, and promise to shed light into some of its properties.
In our experiment, we use a quantum-gas microscope with projected disorder to study the dynamics of out-of-equilibrium bosons in two dimensions, where we observe a remaining memory of the initially prepared state by measuring the evolution of its imbalance. By introducing a second bosonic species unaffected by the disorder potential, an effective small bath has been coupled to the system, for which we measure its effect on the disordered component. In the presence of a big enough bath, the system ultimately loses its imbalance, but for small fractions of the clean component localization seems to survive.