  We exploit the analogy between dynamics of inertial particle pair separation
in a random-in-time flow and the Anderson model of a quantum particle on the
line in a spatially random real-valued potential. Thereby we get an exact
formula for the Lyapunov exponent of pair separation in a special case, and we
are able to generalize the class of solvable models slightly, for potentials
that are real up to a global complex multiplier. A further important result for
inertial particle behavior, supported by analytical computations in some cases
and by numerics more generally, is that of the decay of the Lyapunov exponent
with large Stokes number (quotient of particle relaxation and flow turn-over
time-scales) as Stokes number to the power -2/3.
