Probing the scale invariance of the inflationary power spectrum in expanding quasi-two-dimensional dipolar condensates

TL;DR

This paper explores how dipolar quantum gases can simulate inflationary cosmology, revealing that initial roton minima significantly alter the expected scale invariance of primordial fluctuation spectra.

Contribution

It demonstrates that dipolar Bose-Einstein condensates can serve as laboratory analogues to study modifications in inflationary power spectra due to roton minima.

Findings

Roton minima cause strong deviations from scale invariance.

Dipolar gases can simulate trans-Planckian effects in cosmology.

Experimental setup allows controlled investigation of early universe models.

Abstract

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.