Entanglement in composite free-fermion systems

TL;DR

This paper investigates the entanglement properties in composite free-fermion systems, analyzing how ground-state entanglement entropy and entanglement Hamiltonians behave when metals and insulators are coupled.

Contribution

It introduces a detailed analysis of entanglement entropy and Hamiltonians in fermionic chains with mixed metallic and insulating regions, highlighting their dependence on system parameters.

Findings

Entanglement entropy exhibits specific asymptotic behaviors depending on system parameters.

Distinct features of entanglement Hamiltonians are identified in metallic and insulating subsystems.

The evolution of entanglement entropy after joining different system parts is characterized.

Abstract

We consider fermionic chains where the two halves are either metals with different bandwidths or a metal and an insulator. Both are coupled together by a special bond. We study the ground-state entanglement entropy between the two pieces, its dependence on the parameters and its asymptotic form. We also discuss the features of the entanglement Hamiltonians in both subsystems and the evolution of the entanglement entropy after joining the two parts of the system.