Experimental probes of Stark many-body localization

TL;DR

This paper investigates Stark many-body localization (MBL), demonstrating that experimental probes used for conventional MBL are effective in the Stark MBL setting, and discusses implications for experimental realization and related phenomena.

Contribution

It shows that existing experimental probes can distinguish Stark MBL from non-interacting localization and explores the role of curvature and disorder in reproducing MBL phenomenology.

Findings

DEER response exhibits power-law decay in Stark MBL

Quantum mutual information spreads logarithmically in Stark MBL

No significant differences in MBL measures for softcore bosons with interactions

Abstract

Recent work has focused on exploring many-body localization (MBL) in systems without quenched disorder: one such proposal is Stark MBL in which small perturbations to a strong linear potential yield localization. However, as with conventional MBL, it is challenging to experimentally distinguish between non-interacting localization and true MBL. In this paper we show that several existing experimental probes, designed specifically to differentiate between these scenarios, work similarly in the Stark MBL setting. In particular we show that a modified spin-echo response (DEER) shows clear signs of a power-law decay for Stark MBL while quickly saturating for disorder-free Wannier-Stark localization. Further, we observe the characteristic logarithmic-in-time spreading of quantum mutual information in the Stark MBL regime, and an absence of spreading in a non-interacting Stark-localized system. We also show that there are no significant differences in several existing MBL measures for a system consisting of softcore bosons with repulsive on-site interactions. Lastly we discuss why curvature or small disorder are needed for an accurate reproduction of MBL phenomenology, and how this may be illustrated in experiment. This also connects with recent progress on Hilbert space fragmentation in "fractonic" models with conserved dipole moment, and we suggest this as an auspicious platform for experimental investigations of these phenomena.