Zero-mode entanglement across a conformal defect

Abstract We consider a free-fermion chain with conformal defect that features an extended zero mode, and study the entanglement properties in its mixed ground state. The zero-mode induced degeneracy modifies density of states single-particle spectrum, which can be calculated via full counting statistics. For homogeneous chain, resulting change Rényi entropy is derived analytically for arbitrary subsystem ratios thermodynamic limit. located center, analogous results obtained half-chain entanglement. In particular, we observe parity effects half-chains even/odd sites, do not decay size.