Speaker
Description
Studying quantum fields in strong gravity poses several fundamental questions, like the quantum-classical transition of primordial density perturbations in the early Universe and the information paradox. To understand these questions, in this talk, we consider a massive quantum scalar field in a time-dependent background and study various quantum correlation measures — entanglement entropy, quantum fidelity, Loschmidt echo, etc. The leading order behavior of these measures is found to be related via simple expressions at late times, and also serves as a diagnostic tool for instabilities in the system. We quantify such instabilities in terms of scrambling time and Lyapunov exponents and show that the system mimics classicality under certain conditions. We also show that the entropy scaling oscillates between the area-law and volume-law for a scalar field that undergoes a global quench. We then discuss its implications for the quantum-classical transition of scalar perturbations in the early Universe. [Refs: https://doi.org/10.1103/PhysRevD.107.025003]
