Weak ergodicity breaking from quantum many-body scars Journal Article

Author(s): Turner, Christopher J; Michailidis, Alexios A; Abanin, Dmitry A; Serbyn, Maksym; Papić, Zlatko
Article Title: Weak ergodicity breaking from quantum many-body scars
Affiliation IST Austria
Abstract: The thermodynamic description of many-particle systems rests on the assumption of ergodicity, the ability of a system to explore all allowed configurations in the phase space. Recent studies on many-body localization have revealed the existence of systems that strongly violate ergodicity in the presence of quenched disorder. Here, we demonstrate that ergodicity can be weakly broken by a different mechanism, arising from the presence of special eigenstates in the many-body spectrum that are reminiscent of quantum scars in chaotic non-interacting systems. In the single-particle case, quantum scars correspond to wavefunctions that concentrate in the vicinity of unstable periodic classical trajectories. We show that many-body scars appear in the Fibonacci chain, a model with a constrained local Hilbert space that has recently been experimentally realized in a Rydberg-atom quantum simulator. The quantum scarred eigenstates are embedded throughout the otherwise thermalizing many-body spectrum but lead to direct experimental signatures, as we show for periodic recurrences that reproduce those observed in the experiment. Our results suggest that scarred many-body bands give rise to a new universality class of quantum dynamics, opening up opportunities for the creation of novel states with long-lived coherence in systems that are now experimentally realizable.
Journal Title: Nature Physics
Volume: 14
ISSN: 1745-2473
Publisher: Nature Publishing Group  
Date Published: 2018-05-14
Start Page: 745
End Page: 749
DOI: 10.1038/s41567-018-0137-5
Notes: C.J.T., A.M. and Z.P. acknowledge support from EPSRC grants EP/P009409/1 and EP/M50807X/1, and Royal Society Research Grant RG160635. D.A. acknowledges support from the Swiss National Science Foundation.
Open access: no