  We provide further analytical insights into the newly established
noninteracting (free-fermion) Page curve, focusing on both the kinematic and
dynamical aspects. First, we unveil the underlying canonical typicality and
atypicality for random free-fermion states. The former appears for a small
subsystem and is exponentially weaker than the well-known result in the
interacting case. The latter explains why the free-fermion Page curve differs
remarkably from the interacting one when the subsystem is macroscopically
large, i.e., comparable with the entire system. Second, we find that the
free-fermion Page curve emerges with unexpectedly high accuracy in some simple
tight binding models in long-time quench dynamics. This contributes a rare
analytical result concerning quantum thermalization on a macroscopic scale,
where conventional paradigms such as the generalized Gibbs ensemble and
quasi-particle picture are not applicable.
