University of Leeds
Quantum many-body scars
Abstract: Recent experiments on large chains of Rydberg atoms [H. Bernien et al., Nature 551, 579 (2017)] have demonstrated the possibility of realizing 1D quantum simulators with locally constrained Hilbert spaces. These experiments have revealed surprising signatures of non-ergodic dynamics in an apparently thermalizing quantum system, for example manifested as persistent oscillations following a quench from the initial Neel state of atoms. In this talk I will argue that this phenomenon is a manifestation of a "quantum many-body scar", i.e., a concentration of extensively many eigenstates of the system around special many-body states . The special states are analogues of unstable classical periodic orbits in the single-particle quantum billiards . I will present a model based on a single particle hopping on the Hilbert space graph, which quantitatively captures the scarred wave functions in large systems that can be numerically simulated. These results suggest that scarred many-body bands give rise to a new universality class of quantum dynamics, which is distinct from thermalization or localization, that could be used for creating and manipulating novel states with long-lived coherence in systems that are now available in experiments.
 C. J. Turner, A. A. Michailidis, D. A. Abanin, M. Serbyn, Z. Papić, Nat. Phys, 14, 745 (2018).
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