  We consider an analogue de Sitter cosmos in an expanding
quasi-two-dimensional Bose-Einstein condensate with dominant dipole-dipole
interactions between the atoms or molecules in the ultracold gas. It is
demonstrated that a hallmark signature of inflationary cosmology, the scale
invariance of the power spectrum of inflaton field correlations, experiences
strong modifications when, at the initial stage of expansion, the excitation
spectrum displays a roton minimum. Dipolar quantum gases thus furnish a viable
laboratory tool to experimentally investigate, with well-defined and
controllable initial conditions, whether primordial oscillation spectra
deviating from Lorentz invariance at trans-Planckian momenta violate standard
predictions of inflationary cosmology.
