The role of Causality in Tunable Fermi Gas Condensates

We develop a new formalism for the description of the condensates of cold Fermi atoms whose speed of sound can be tuned with the aid of a narrow Feshbach resonance. We use this to look for spontaneous phonon creation that mimics spontaneous particle creation in curved space-time in Friedmann-Robertson-Walker and other model universes.Comment: 9 pages, 2 figures. In v.3 the formalism is different from the existing arXiv versions, but the final results are unchanged. Title changed, one author added. The article will be published in the special edition of Journal of Physics: Condensed Matter on "Condensed matter analogues of cosmology