Entanglement Entropy in Flat Holography

Understand

BMS symmetry, which is the asymptotic symmetry at null infinity of flat spacetime, is an important input for flat holography.

• In this paper, we give a holographic calculation of entanglement entropy and R\'{e}nyi entropy in three dimensional Einstein gravity and Topologically Massive Gravity.
• The geometric picture for the entanglement entropy is the length of a spacelike geodesic which is connected to the interval at null infinity by two null geodesics.
• The spacelike geodesic is the fixed points of replica symmetry, and the null geodesics are along the modular flow.