Randomly measured quantum particle

Abstract

We consider the motion of a quantum particle whose position is measured in random places at random moments in time. We show that a freely moving particle measured in this way undergoes superdiffusion, while a charged particle moving in a magnetic field confined to the lowest Landau level undergoes conventional diffusion. We also look at a particle moving in one dimensional space in a random time-independent potential, so that it is Anderson localized, which is also measured at random points in space and randomly in time. We find that random measurements break localization and this particle also undergoes diffusion. To address these questions, we develop formalism similar to that employed when studying classical and quantum problems with time-dependent noise.