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Quantum many-body scars: a new form of ergodicity breaking in a Rydberg-atom quantum simulator

November 6, 2018 - 11:00am
Speaker: 
Dmitry Abanin
Institution: 
University of Geneva
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 of 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 wave functions 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 been recently experimentally realized in a
Rydberg-atom quantum simulator. The quantum scarred eigenstates are
embedded throughout the otherwise ergodic 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.

Host:Jay Sau

2205 John S. Toll Physics Building (CMTC Conference Room)
20742