Seminars & Lectures
| * TITLE | Experimental Quantum Cosmology | ||||||
|---|---|---|---|---|---|---|---|
| * SPEAKERS | |||||||
|
|||||||
| * HOST(Applicant) | |||||||
|
|||||||
| * DATE / TIME | 2017-08-16, am 11:00 ~ | ||||||
| * ABSTRACT | |||||||
| Cosmology in the early universe is a branch of physics which is, for all too obvious reasons, removed far from experiment. To use a concise formulation of the primary dilemma which cosmology faces, there exists nothing like the possibility of \\\"reproducing\\\" experiments, because there has in fact \\\"only ever been one experiment, still running, and we are latecomers watching from the back.\\\" While there can be no truly experimental cosmology, as regards, in particular, the reproduction of the (presumed) extreme conditions which prevailed in the early stages of the universe, one can endeavor to look for analogous phenomena in condensed matter or cold atom experiments, which are indeed reproducible, and can be done at energy scales smaller by many orders of magnitude. Now, taking up this lead, we provide a feasible experimental scheme for exploring the influence of trans-Planckian physics on a hallmark signature of inflationary cosmology, the scale invariance of the power spectrum of inflaton field correlations. We consider an analogue de Sitter cosmos in an expanding quasi-two-dimensional dipolar Bose-Einstein condensate formed by ultracold atoms or molecules, and demonstrate that the scale invariance of the power spectrum experiences strong modifications when at the initial stage of expansion the excitation spectrum displays a so-called roton minimum in the (analogue) trans-Planckian sector. We thus demonstrate that dipolar quantum gases furnish a viable laboratory tool to experimentally investigate, with well-defined and controllable initial conditions (at the \\\"big bang\\\"), whether primordial oscillation spectra deviating from Lorentz invariance at trans-Planckian momenta violate standard predictions of inflationary cosmology. Importantly, because scale invariance is a kinematical phenomenon of quantum fields in a pre-given, fixed de Sitter spacetime, these experimental investigations may have important repercussions for actual cosmology and the interpretation of its observational data. |
|||||||
