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Entanglement of midspectrum eigenstates of chaotic many-body systems: Reasons for deviation from random ensembles (2008.12782v2)
Published 28 Aug 2020 in cond-mat.stat-mech and cond-mat.dis-nn
Abstract: Eigenstates of local many-body interacting systems that are far from spectral edges are thought to be ergodic and close to being random states. This is consistent with the eigenstate thermalization hypothesis and volume-law scaling of entanglement. We point out that systematic departures from complete randomness are generically present in mid-spectrum eigenstates, and focus on the departure of the entanglement entropy from the random-state prediction. We show that the departure is (partly) due to spatial correlations and due to orthogonality to the eigenstates at the spectral edge, which imposes structure on the mid-spectrum eigenstates.