Antipersistent random walk in a two state flashing magnetic potential.

We reveal the subdiffusive dynamics of paramagnetic colloids subjected to a two state flashing potential generated by periodic modulation of a magnetic bubble lattice. The particles perform a random walklike motion with antipersistent nature, showing for certain field parameters a crossover from subdiffusive to an enhanced diffusive behavior. We elucidate the stationary nature (no aging) of the subdiffusive process and stress its similarity with the random walk on a random walk model.