Absence of full many-body localization in the disordered Hubbard chain

TL;DR

This study numerically investigates the disordered Hubbard chain, revealing that charge can be localized while spin remains ergodic under charge disorder, indicating the absence of full many-body localization in this model.

Contribution

It demonstrates that in the disordered Hubbard model, charge and spin localization behaviors differ, challenging the assumption of full MBL with charge disorder alone.

Findings

Charge is non-ergodic under charge disorder.

Spin remains delocalized and ergodic with charge disorder.

Full MBL can be achieved with spin-dependent disorder.

Abstract

We present numerical results within the one-dimensional disordered Hubbard model for several characteristic indicators of the many-body localization (MBL). Considering traditionally studied charge disorder (i.e., the same disorder strength for both spin orientations) we find that even at strong disorder all signatures consistently show that while charge degree of freedom is non-ergodic, the spin is delocalized and ergodic. This indicates the absence of the full MBL in the model that has been simulated in recent cold-atom experiments. Full localization can be restored if spin-dependent disorder is used instead.