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arXiv · 1409.1224

Entanglement Entropy Scaling Laws and Eigenstate Typicality in Free Fermion Systems

Hsin-Hua Lai·Kun Yang
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Abstract

We demonstrate that the entanglement entropy area law for free fermion ground states and the corresponding volume law for highly excited states are related by a position-momentum duality, thus of the same origin. For a typical excited state in the thermodynamic limit, we further show that the reduced density matrix of a subsystem approaches thermal density matrix, provided the subsystem's linear size is small compared to that of the whole system in all directions, a property we dub eigenstate typicality. This provides an explicit example of thermalization via entanglement, and reveals how statistical physics emerges from a single eigenstate by tracing out a large number of degrees of freedom.

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Hsin-Hua Lai, Kun Yang. 2015-02-24. Entanglement Entropy Scaling Laws and Eigenstate Typicality in Free Fermion Systems. https://doi.org/10.1103/physrevb.91.081110

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