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.
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.
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Turner C, Michailidis A, Abanin D, Serbyn M, Papić Z. Weak ergodicity breaking from quantum many-body scars. Nature Physics. 2018;14:745-749. doi:10.1038/s41567-018-0137-5
Turner, C., Michailidis, A., Abanin, D., Serbyn, M., & Papić, Z. (2018). Weak ergodicity breaking from quantum many-body scars. Nature Physics, 14, 745–749. https://doi.org/10.1038/s41567-018-0137-5
Turner, Christopher, Alexios Michailidis, Dmitry Abanin, Maksym Serbyn, and Zlatko Papić. “Weak Ergodicity Breaking from Quantum Many-Body Scars.” Nature Physics 14 (2018): 745–49. https://doi.org/10.1038/s41567-018-0137-5.
C. Turner, A. Michailidis, D. Abanin, M. Serbyn, and Z. Papić, “Weak ergodicity breaking from quantum many-body scars,” Nature Physics, vol. 14, pp. 745–749, 2018.
Turner C, Michailidis A, Abanin D, Serbyn M, Papić Z. 2018. Weak ergodicity breaking from quantum many-body scars. Nature Physics. 14, 745–749.
Turner, Christopher, et al. “Weak Ergodicity Breaking from Quantum Many-Body Scars.” Nature Physics, vol. 14, Nature Publishing Group, 2018, pp. 745–49, doi:10.1038/s41567-018-0137-5.