  We show that for a subdiffusive continuous time random walk with scale-free
waiting time distribution the first-passage dynamics on a finite interval can
be optimised by introduction of a piecewise linear potential barrier.
Analytical results for the survival probability and first-passage density based
on the fractional Fokker-Planck equation are shown to agree well with Monte
Carlo simulations results. As an application we discus an improved deign for
efficient translocation of gradient copolymers compared to homopolymer
translocation in a quasi-equilibrium approximation.
