Onsager's Scars in Disordered Spin Chains
Abstract
We propose a class of nonintegrable quantum spin chains that exhibit quantum manybody scars even in the presence of disorder. With the use of the socalled Onsager symmetry, we construct scarred models for arbitrary spin quantum number S . There are two types of scar states, namely, coherent states associated with an Onsageralgebra element and onemagnon scar states. While both of them are highly excited states, they have arealaw entanglement and can be written as a matrix product state. Therefore, they explicitly violate the eigenstate thermalization hypothesis. We also investigate the dynamics of the fidelity and entanglement entropy for several initial states. The results clearly show that the scar states are trapped in a perfectly periodic orbit in the Hilbert subspace and never thermalize, whereas other generic states do rapidly. To our knowledge, our model is the first explicit example of disordered quantum manybody scarred models.
 Publication:

Physical Review Letters
 Pub Date:
 May 2020
 DOI:
 10.1103/PhysRevLett.124.180604
 arXiv:
 arXiv:1912.13399
 Bibcode:
 2020PhRvL.124r0604S
 Keywords:

 Quantum Physics;
 Condensed Matter  Statistical Mechanics;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 5+7 pages, 4+5 figures