Entanglement Hamiltonians and the quasiparticle picture

TL;DR

This paper derives an analytic expression for the entanglement Hamiltonian after a quantum quench in non-interacting fermionic models, extending the quasiparticle picture to operators and aiding experimental engineering.

Contribution

It introduces a novel analytic formula for the entanglement Hamiltonian in non-equilibrium fermionic systems, bridging a gap in microscopic model understanding.

Findings

Analytic EH formula valid in ballistic scaling regime.

Extension of quasiparticle picture to operators.

Potential applications in quantum optics experiments.

Abstract

The entanglement Hamiltonian (EH) provides the most comprehensive characterization of bipartite entanglement in many-body quantum systems. Ground states of local Hamiltonians inherit this locality, resulting in EHs that are dominated by local, few-body terms. Unfortunately, in non-equilibrium situations, analytic results are rare and largely confined to continuous field theories, which fail to accurately describe microscopic models. To address this gap, we present an analytic result for the EH following a quantum quench in non-interacting fermionic models, valid in the ballistic scaling regime. The derivation adapts the celebrated quasiparticle picture to operators, providing detailed insights into its physical properties. The resulting analytic formula serves as a foundation for engineering EHs in quantum optics experiments.