CMT Forum: Jonathan Classen-Howes

In this talk, I will introduce an SU(M)-symmetric disordered bipartite spin model which, although superficially similar to the Sachdev-Ye model, has several markedly different and unusual properties for M>2. In particular, the model provides a rare example of a non-local system that violates the eigenstate thermalization hypothesis via Hilbert space fragmentation. This fragmentation stems from the model’s non-trivial nullspace, which is composed of frustration-free states and grows exponentially in dimension with system size. Furthermore, the fragmentation is confined to only certain SU(M) quantum number sectors, in which it completely freezes the model’s dynamics. In addition to demonstrating these properties, I will explore the connection between the model’s commutant algebra and the Read-Saleur commutant algebra of certain nearest-neighbour models, such as the spin-1 biquadratic spin chain. I will conclude by showing how the Shiraishi-Mori embedding formalism can be applied to the model to turn some of the nullspace states into quantum many-body scars.

Link: https://arxiv.org/abs/2403.15270