We uncover various novel aspects of the entanglement of free fermions at finite temperature on the circle. The modular flow involves a bi-local coupling between a discrete but infinite set of points, even for a single interval. The modular Hamiltonian transitions from locality to complete non-locality as a function of temperature. We derive the entanglement and relative entropies, and comment on the applications to bulk reconstruction in higher spin holography.
Based on [1905.05768,1906.02207].
