Agenda

Résumé : Generic many-body quantum evolution encodes local information, making them practically inaccessible. The effective information loss underlies thermalisation. Meanwhile, when a quantum object is observed by a macroscopic apparatus, the opposite happens: some classical information becomes widely accessible. Many observers can independently retrieve it from small fractions of the environment. In this talk we shall advocate that the two distinct behaviours are “phases of quantum information”, of which a quantitative definition will be proposed for a general open-system setup. We shall then present toy models that exhibit sharp transitions between those phases. At last we shall discuss speculatively how hard it is to observe these transitions, and conceptual implications of our findings.
Refs: https://arxiv.org/abs/2312.04284 https://arxiv.org/abs/2305.03694