  Expansion of a degenerate Bose gas released from a pancakelike trap is
numerically simulated under the assumption of separation of the motion in the
plane of the loose initial trapping and the motion in the direction of the
initial tight trapping. The initial conditions for the phase fluctuations are
generated using the extension to the two-dimensional case of the description of
the phase noise by the Ornstein-Uhlenbeck stochastic process. The numerical
simulations, taking into account both the finite size of the two-dimensional
system and the atomic interactions, which cannot be neglected on the early
stage of expansion, did not reproduce the scaling law for the peaks in the
density fluctuation spectra experimentally observed by Choi, Seo, Kwon, and
Shin [Phys. Rev. Lett. 109, 125301 (2012)]. The latter experimental results may
thus require an explanation beyond our current assumptions.
