LAUSR

When a group of compactly packed free fermions is allowed to spread over an empty one-dimensional lattice, the spreading particles can create entanglement between different parts of the lattice. We show, although breaking of translational invariance (TI) of the lattice by disorder slows down the spreading of local observables, the entanglement entropy of a subsystem can nonetheless receive a remarkable enhancement as long as the subsystem lies within the single-particle localization length. We show the main mechanism behind this enhancement is the reentrant exchange of particles between the subparts due to transport of mutual information due to backscattering. We discuss the length and timescales relevant to the phenomenon. We study the phenomenon for breaking of TI by both quasiperiodic and random potentials. We further explore the effect of randomness only in the initial state. This also exhibits a similar enhancement effect even in a TI lattice. We also touch upon the special case of periodic potential where qualitatively similar phenomenology emerges, although the coherence in the backscattering in this case leads to effects not captured by our simple yet generic picture.