[sém. théorie] Open quantum systems and the generation of cosmological inhomogeneities

par Thomas Colas (IAS Orsay)

mercredi 21 oct. 2020, 11:00 → 11:45 Europe/Paris

Zoom

In the standard model of cosmology, cosmological inhomogeneities that seed CMB anisotropies and the LSS originate from quantum fluctuations of the primordial vacuum amplified during inflation. Understanding the quantum state of these fluctuations in the early universe is then of major concern to accurately predict its later history. This quantum state is well known for single-field inflation where the dynamics is driven by a unique scalar field. However, the situation is more subtle when several fields interact, in particular in the presence of an unobservable sector. In this talk, I will present how to characterise the quantum information of a generic two-field system and discuss the case where the observer only accesses the information from one of the fields, the other playing the role of an unobservable environment. In this setting, quantum decoherence takes place and information is lost in the environmental degrees of freedom. The consequences of this loss of coherence on the generation of cosmological inhomogeneities will be explored in the simple case of two test-fields in a de Sitter background.

ZOOM link: https://univ-grenoble-alpes-fr.zoom.us/j/95773689216?pwd=M04zeTUzcHdBa042ZllzbHExQVBIZz09