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Particle fluctuations and the failure of simple effective models for many-body localized phases

by Maximilian Kiefer-Emmanouilidis, Razmik Unanyan, Michael Fleischhauer, Jesko Sirker

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Submission summary

Authors (as registered SciPost users): Maximilian Kiefer-Emmanouilidis
Submission information
Preprint Link: scipost_202111_00010v2  (pdf)
Date accepted: 2021-12-08
Date submitted: 2021-12-07 00:49
Submitted by: Kiefer-Emmanouilidis, Maximilian
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Atomic, Molecular and Optical Physics - Theory
  • Condensed Matter Physics - Theory
Approaches: Theoretical, Computational


We investigate and compare the particle number fluctuations in the putative many-body localized (MBL) phase of a spinless fermion model with potential disorder and nearest-neighbor interactions with those in the non-interacting case (Anderson localization) and in effective models where only interaction terms diagonal in the Anderson basis are kept. We demonstrate that these types of simple effective models cannot account for the particle number fluctuations observed in the MBL phase of the microscopic model. This implies that assisted and pair hopping terms---generated when transforming the microscopic Hamiltonian into the Anderson basis---cannot be neglected even at strong disorder and weak interactions. As a consequence, it appears questionable if the microscopic model possesses an exponential number of exactly conserved {\it local} charges. If such a set of conserved local charges does not exist, then particles are expected to ultimately delocalize for any finite disorder strength.

Published as SciPost Phys. 12, 034 (2022)

Author comments upon resubmission

We have followed the Editor’s recommendation to make an additional minor change and have modified the manuscript accordingly.

List of changes

On page 2 we have removed Eq. (2) and have reformulated this part as suggested.

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