Bipartite Sachdev-Ye models with Read-Saleur symmetries

Journal article

We introduce an SU⁡(𝑀)-symmetric disordered bipartite spin model with unusual characteristics. Although superficially similar to the Sachdev-Ye (SY) model, it has several markedly different properties for 𝑀≥3. In particular, it has a large nontrivial nullspace whose dimension grows exponentially with system size. The states in this nullspace are frustration-free and are ground states when the interactions are ferromagnetic. The exponential growth of the nullspace leads to Hilbert-space fragmentation and a violation of the eigenstate thermalization hypothesis. We demonstrate that the commutant algebra responsible for this fragmentation is a nontrivial subalgebra of the Read-Saleur commutant algebra of certain nearest-neighbor models such as the spin-1 biquadratic spin chain. We also discuss the low-energy behavior of correlations for the disordered version of this model in the limit of a large number of spins and large 𝑀, using techniques similar to those applied to the SY model. We conclude by generalizing the Shiraishi-Mori embedding formalism to nonlocal models, and apply it to turn some of our nullspace states into quantum many-body scars.

Authors: Classen-Howes, J; Fendley, P; Pandey, A; Parameswaran, SA

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B: Condensed Matter and Materials Physics
• Volume: 110
• Issue: 12
• Article number: 125140
• Publication date: 2024-09-19
• Acceptance date: 2024-08-30
• DOI: 10.1103/PhysRevB.110.125140
• EISSN: 1550-235X
• ISSN: 1098-0121
• Language: English