  Early during the era of cosmic inflation, rotational invariance may have been
broken, only later emerging as a feature of low-energy physics. This motivates
ongoing searches for residual signatures of anisotropic space-time, for example
in the power spectrum of the cosmic microwave background. We propose that
dipolar Bose-Einstein condensates (BECs) furnish a laboratory quantum
simulation platform for the anisotropy evolution of fluctuation spectra during
inflation, exploiting the fact that the speed of dipolar condensate sound waves
depends on direction. We construct the anisotropic analogue space-time metric
governing sound, by linking the time-varying strength of dipolar and contact
interactions in the BEC to the scale factors in different coordinate
directions. Based on these, we calculate the dynamics of phonon power spectra
during an inflation that renders the initially anisotropic universe isotropic.
We find that the expansion speed provides an experimental handle to control and
study the degree of final residual anisotropy. Gravity analogues using dipolar
condensates can thus provide tuneable experiments for a field of cosmology that
was until now confined to a single experiment, our universe.
