Slow dynamics from a nested hierarchy of frozen states

Marić, Vanja (author), Paljk, Luka (author), Zadnik, Lenart (author)

We identify the mechanism of slow heterogeneous relaxation in quantum kinetically constrained models (KCMs) in which the potential energy strength is controlled by a coupling parameter. The regime of slow relaxation includes the large-coupling limit. By expanding around that limit, we reveal a nested hierarchy of states that remain frozen on time scales determined by powers of the coupling. The classification of such states, together with the evolution of their Krylov complexity, reveals that these time scales are related to the distance between the sites where facilitated dynamics is allowed by the kinetic constraint. While correlations within frozen states relax slowly and exhibit metastable plateaus that persist on time scales set by powers of the coupling parameter, the correlations in the rest of the states decay rapidly. We compute the plateau heights of correlations across all frozen states up to second-order corrections in the inverse coupling. Our results explain slow relaxation in quantum KCMs and elucidate dynamical heterogeneity by relating the relaxation times to the spatial separations between the active regions.

• Language: English
• Keywords: nonequilibrium systems, nonequilibrium statistical mechanics, quantum spin models, kinetically constrained models
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: Str. 024313-1-024313-10
• Numbering: Vol. 113, iss. 2
• PID: 20.500.12556/RUL-180950
• UDC: 536.93
• ISSN on article: 2469-9950
• DOI: 10.1103/vc42-9kb1
• COBISS.SI-ID: 272413955
• Publication date in RUL: 20.03.2026

Record is a part of a journal

• Title: Physical review
• Publisher: American Physical Society
• ISSN: 2469-9950
• COBISS.SI-ID: 2997348

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: neravnovesni sistemi, neravnovesna statistična mehanika, kvantni spinski modeli