  A randomly walking quantum particle searches in Grover's $\Theta(\sqrt{N})$
iterations for a marked vertex on the complete graph of $N$ vertices by
repeatedly querying an oracle that flips the amplitude at the marked vertex,
scattering by a "coin" flip, and hopping. Physically, however, potential energy
barriers can hinder the hop and cause the search to fail, even when the
amplitude of not hopping decreases with $N$. We correct for these errors by
interpreting the quantum walk search as an amplitude amplification algorithm
and modifying the phases applied by the coin flip and oracle such that the
amplification recovers the $\Theta(\sqrt{N})$ runtime.
