  In the context of an isolated three-dimensional noninteracting fermionic
lattice system, we study the effects of a sudden quantum quench between a
disorder-free situation and one in which disorder results in a mobility edge
and associated Anderson localization. Salient post-quench features hinge upon
the overlap between momentum states and post-quench eigenstates and whether
these latter states are extended or localized. We find that the post-quench
momentum distribution directly reflects these overlaps. For the local density,
we show that disorder generically prevents the equilibration of quantum
expectation values to a steady state and that the persistent fluctuations have
a nonmonotonic dependence on the strength of disorder. We identify two distinct
types of fluctuations, namely, temporal fluctuations describing the
time-dependent fluctuations of the local density around its time average and
sample-to-sample fluctuations characterizing the variations of these time
averages from one realization of disorder to another. We demonstrate that both
of these fluctuations vanish for extremely extended as well as extremely
localized states, peaking at some intermediate value.
