A possible mechanism of superdiffusion of ultracold atoms in a one-dimensional polarization optical lattice, observed experimentally in Phys. Rev. Lett. 108, 093002 (2012), is suggested. The analysis is based on a consideration of anomalous diffusion in a fractal comb [Phys. Rev. E 83, 052106 (2011)]. It is shown that the transport exponent is determined by the fractal geometry of the comb due to recoil distributions resulting in Lévy flights of atoms.

• Received 23 May 2012

DOI:https://doi.org/10.1103/PhysRevE.86.032101