Entanglement of exact excited states of Affleck-Kennedy-Lieb-Tasaki models: Exact results, many-body scars, and violation of the strong eigenstate thermalization hypothesis
By Sanjay Moudgalya, N. Regnault, Bogdan Andrei Bernevig. Physical review B, 2018
265 citations recorded by the source corpus.
We obtain multiple exact results on the entanglement of the exact excited states of nonintegrable models we introduced in Phys. Rev. B 98, 235155 (2018)10.1103/PhysRevB.98.235155. We first discuss a general formalism to analytically compute the entanglement spectra of exact excited states using matrix product states and matrix product operators and illustrate the method by reproducing a general result on single-mode excitations. We then apply this technique to analytically obtain the entanglement spectra of the infinite tower of states of the spin-S AKLT models in the zero and finite energy density limits. We show that in the zero energy density limit, the entanglement spectra of the tower of states are multiple shifted copies of the ground-state entanglement spectrum in the thermodynamic limit. We show that such a resemblance is destroyed at any nonzero energy density. Furthermore, the entanglement entropy S of the states of the tower that are in the bulk of the spectrum is subthermal S∝logL, as opposed to a volume law S∝L, thus indicating a violation of the strong eigenstate thermalization hypothesis (ETH). These states are examples of what are now called many-body scars. Finally, we analytically study the finite-size effects and symmetry-protected degeneracies in the entanglement spectra of the excited states, extending the existing theory.
Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/8af51a9df135d7cc3c6a34882d9934a384d21ebf
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In Condensed Matter Physics
Citations in the corpus
- Quantum many-body scars and weak breaking of ergodicity (2020, methodology): “[37] Sanjay Moudgalya, Nicolas Regnault, and B.”
- Statistical localization: From strong fragmentation to strong edge modes (2019, unknown): “[35] Sanjay Moudgalya, Nicolas Regnault, and B.”
- Quantum Many-Body Scars: A Quasiparticle Perspective (2022, background): “While a variety of mechanisms for quantum many-body scars have been proposed, a ubiquitous one is the emergence of a small subset of stable quasiparticles, out of which special many-particle states throughout the many-body spectrum can be constructed (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, ”
- Ergodicity Breaking Arising from Hilbert Space Fragmentation in Dipole-Conserving Hamiltonians (2019, background): “[34] Sanjay Moudgalya, Nicolas Regnault, and B.”