  The evolution of quantum walk on a finite wire under a small increment of
vector potential $\alpha$ can exhibit intrinsic quantum oscillation of the two
topologically protected bound states corresponding to the Majorana modes. By
tuning an external electric field corresponding to the addition of an $\alpha$
impulse at the end of each intrinsic period, the intrinsic oscillation is
enveloped by a beat modulation with a longer period. This beat oscillation is
useful in the preparation of decoherence-free qubit in trapped ion chain and
may be observed in several experiments.
