Entanglement and topological interfaces

Understand

In this paper we consider entanglement entropies in two-dimensional conformal field theories in the presence of topological interfaces.

• Tracing over one side of the interface, the leading term of the entropy remains unchanged.
• The interface however adds a subleading contribution, which can be interpreted as a relative (Kullback-Leibler) entropy with respect to the situation with no defect inserted.
• Reinterpreting boundaries as topological interfaces of a chiral half of the full theory, we rederive the left/right entanglement entropy in analogy with the interface case.