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.
Recommended Citation
M. Puschmann et al., "Collective Modes at a Disordered Quantum Phase Transition," Physical Review Letters, vol. 125, no. 2, American Physical Society (APS), Jul 2020.
The definitive version is available at https://doi.org/10.1103/PhysRevLett.125.027002
Department(s)
Physics
Research Center/Lab(s)
Center for High Performance Computing Research
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 (APS), All rights reserved.
Publication Date
10 Jul 2020
PubMed ID
32701338
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.