Adiabatic freezing of entanglement with insertion of defects in a one-dimensional Hubbard model

TL;DR

This paper investigates the ground state phases of a doped one-dimensional Hubbard model, revealing a phenomenon called adiabatic freezing where entanglement remains invariant under parameter changes, especially in the metallic phase.

Contribution

It introduces the concept of adiabatic freezing of entanglement in the Hubbard model and characterizes its occurrence across different phases, highlighting its novelty.

Findings

Entanglement is polynomially decaying and frozen in the metallic phase.

Exponential decay of entanglement occurs in phase-separation and spin-gap phases.

Multipartite entanglement remains frozen in the spin-gap phase at low electron densities.

Abstract

We report on ground state phases of a doped one-dimensional Hubbard model, which for large onsite interactions is governed by the $t$-$J$ Hamiltonian, where the extant entanglement is immutable under perturbative or sudden changes of system parameters, a phenomenon termed as adiabatic freezing. We observe that in the metallic Luttinger liquid phase of the model bipartite entanglement decays polynomially and is adiabatically frozen, in contrast to the variable, exponential decay in the phase-separation and superconducting spin-gap phases. Significantly, at low fixed electron densities, the spin-gap phase shows remarkable affinity to doped resonating valence bond gas, with multipartite entanglement frozen across all parameter space. We note that entanglement, in general, is sensitive to external perturbation, as observed in several systems, and hitherto, no such invariance or freezing behavior has been reported.