Challenges to observation of many-body localization

Many-body localization (MBL) freezes the dynamics of a disordered quantum interacting system, inhibiting thermalization and resulting in a persistent memory of the initial state. Here, with the help of extensive numerical simulations, the authors find slow decay of the imbalance, a quantity often employed in experimental studies of MBL, even though the disorder strength considerably exceeds the current estimates of the position of the MBL transition. This suggests a slow approach to thermal equilibrium and identifies challenges for unequivocal numerical and experimental demonstrations of MBL.