Information transport and transport-induced entanglement in open fermion chains

TL;DR

This paper investigates how information and entanglement propagate in open fermion chains under nonequilibrium conditions, introducing an information lattice framework that links measurable noise and particle currents to information flow and entanglement.

Contribution

It develops a novel information lattice approach to analyze information transport and entanglement in open quantum systems using Lindblad equations and noise measurements.

Findings

Information currents can be experimentally accessed via noise measurements.

Impurities and asymmetries enable information flow and entanglement between chain ends.

Clean symmetric chains shield information currents from entering the lattice.

Abstract

Understanding the entanglement dynamics in quantum many-body systems under steady-state transport conditions is an actively pursued challenging topic. Hydrodynamic equations, akin to transport equations for charge or heat, would be of great interest but face severe challenges because of the inherent nonlocality of entanglement and the difficulty of identifying conservation laws. We show that progress is facilitated by using information as key quantity related to - but distinct from - entanglement. Employing the recently developed "information lattice" framework, we characterize spatially and scale-resolved information currents in nonequilibrium open quantum systems. Specifically, using Lindblad master equations, we consider noninteracting fermion chains coupled to dissipative reservoirs. By relating the information lattice to a noise lattice constructed from particle-number fluctuations, we show that information is experimentally accessible via noise easurements. Similarly, local information currents can be obtained by measuring particle currents, onsite occupations, and covariances of particle numbers and/or particle currents. Using the fermionic negativity to quantify bipartite entanglement, we also study transport-induced entanglement and its relation to information currents. For a clean particle-hole symmetric chain, we find that information currents are shielded from entering the information lattice. Impurities or particle-hole asymmetry break this effect, causing information current flow and entanglement between end segments of the chain. Our work opens the door to systematic investigations of information transport and entanglement generation in driven open quantum systems far from equilibrium.