Lenart Zadnik
(SISSA)

 

Abstract: The large-anisotropy limit of the anisotropic Heisenberg spin-1/2 chain gives rise to the so-called folded XXZ model. This talk will mainly be a summary of what is and what is not yet known about this kinetically constrained model, and of a rich palette of phenomena that emerge in it. I will provide a brief explanation of the folded model's origin, of its symmetries, of the quasiparticle content constituting its Bethe Ansatz solution, and of what is still not understood. I will explain how the symmetries emergent in the large anisotropy limit of the Heisenberg model result in a rich Hilbert space structure, which exhibits weak fragmentation and a Fibonacci sector of jammed configurations. Jammed states in the latter sector exhibit a somewhat counterintuitive dynamical phenomenon, in which a localised perturbation can have everlasting effects. Finally, if time permits, I will also briefly comment on the subject of semilocal charges that arise in the folded XXZ model and similar kinetically constrained models.