Robust quantum many-body scars in fracton systems. (arXiv:1903.06173v1 [cond-mat.stat-mech])

We study a one-dimensional translation-invariant Floquet quantum circuit
model constrained to conserve a $U(1)$ charge and its dipole moment. We
demonstrate that the Floquet spectrum contains quantum many-body scars, a small
set of localized states in an otherwise thermalizing spectrum. These states are
directly experimentally relevant due to their high overlap with easily-prepared
product states. Moreover, the model is quite generic, since the Floquet
operator is made out of random unitary matrices. We explain the origin of these
scar states in terms of a newly discovered mechanism for localization, thereby
providing a detailed conceptual understanding of how scars can robustly arise
in systems with constrained quantum dynamics.

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