Quantum Entanglement in Multi-field Inflation
  We study the emergence of quantum entanglement in multi-field inflation. In
this scenario, the perturbations of one field contribute to the observable
curvature perturbation, while multi-field dynamics with the other fields affect
the curvature perturbation through particle production and entanglement. We
develop a general formalism which defines the quantum entanglement between the
perturbations of the multiple fields both in the Heisenberg and Schr\"odinger
pictures, and show that entanglement between different fields can arise
dynamically in the context of multi-field inflationary scenarios. We also
present a simple model in which a sudden change in the kinetic matrix of the
scalar fields generates entanglement and an oscillatory feature appears in the
power spectrum of the inflaton perturbation.
