Abstract

We study the collective excitations, i.e., the Goldstone (phase) mode and the Higgs (amplitude) mode, near the superfluid-Mott glass quantum phase transition in a two-dimensional system of disordered bosons. Using Monte Carlo simulations as well as an inhomogeneous quantum mean-field theory with Gaussian fluctuations, we show that the Higgs mode is strongly localized for all energies, leading to a noncritical scalar response. In contrast, the lowest-energy Goldstone mode undergoes a striking delocalization transition as the system enters the superfluid phase. We discuss the generality of these findings and experimental consequences, and we point out potential relations to many-body localization.

Department(s)

Physics

Comments

This work was supported by the NSF under Grants No. DMR-1506152, No. DMR-1828489, No. PHY-1125915, and No. PHY-1607611, by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under Grant No. 312352/2018-2, and by FAPESP under Grants No. 2015/23849-7 and No. 2016/10826-1.

International Standard Serial Number (ISSN)

0031-9007; 1079-7114

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2020 American Physical Society, All rights reserved.

Publication Date

10 Jul 2020

PubMed ID

32701338

Included in

Physics Commons

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