Entanglement Hamiltonian in the non-Hermitian SSH model

2024/02/07 by Federico Rottoli, Michele Fossati, Rottoli, Federico +3 · 5 citations
Physics and Astronomy · #Quantum Mechanics and Non-Hermitian Physics #Quantum many-body systems #Noncommutative and Quantum Gravity Theories

paper · pdf · doi:10.1088/1742-5468/ad4860

Abstract

Abstract Entanglement Hamiltonians provide the most comprehensive characterisation of entanglement in extended quantum systems. A key result in unitary quantum field theories is the Bisognano-Wichmann theorem, which establishes the locality of the entanglement Hamiltonian. In this work, our focus is on the non-Hermitian Su-Schrieffer-Heeger (SSH) chain. We study the entanglement Hamiltonian both in a gapped phase and at criticality. In the gapped phase we find that the lattice entanglement Hamiltonian is compatible with a lattice Bisognano-Wichmann result, with an entanglement temperature linear in the lattice index. At the critical point, we identify a new imaginary chemical potential term absent in unitary models. This operator is responsible for the negative entanglement entropy observed in the non-Hermitian SSH chain at criticality.

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