Boosting entanglement growth of many-body localization by superpositions of disorder

TL;DR

This paper proposes a modified quantum algorithm that uses measurements on an ancilla in superposition to enhance entanglement growth in many-body localized systems, revealing quantum interference effects that boost dephasing.

Contribution

It introduces a measurement-based modification to existing algorithms, enabling the study of conditional dynamics and interference effects in MBL systems.

Findings

Enhanced entanglement growth in deep MBL phase

Quantum interference amplifies dephasing effects

Observed entanglement boost beyond deep MBL regime in simulations

Abstract

Many-body localization (MBL) can occur when strong disorders prevent an interacting system from thermalization. To study the dynamics of such systems, it is typically necessary to perform an ensemble average over many different disorder configurations. Previous works have utilized an algorithm in which different disorder profiles are mapped into a quantum ancilla. By preparing the ancilla in a quantum superposition state, quantum parallelism can be harnessed to obtain the ensemble average in a single computation run. In this work, we modify this algorithm by performing a measurement on the ancilla. This enables the determination of conditional dynamics not only by the ensemble average but also by the quantum interference effect. Using a phenomenological analysis based on local integrals of motion, we demonstrate that this protocol can lead to an enhancement of the dephasing effect and a boost in the entanglement growth for systems in the deep MBL phase. We also present numerical simulations of the random XXZ model where this enhancement is also present in a smaller disorder strength, beyond the deep MBL regime.