Talks

Power-law banded random matrix ensemble as a model for quantum many-body Hamiltonians

Hamiltonians of one-dimensional, disordered single-particle systems with long-range hopping terms can naturally be modeled by power-law banded random matrices. In this picture, the phase diagram of a power-law banded random matrix ensemble show ergodic, weakly ergodic, multifractal, and localized phases. Motivated by recent developments on ergodicity breaking and localization in interacting quantum many-body systems, we explore many-body interpretations of the power-law banded random matrix ensemble. We discuss a number of ways to label the basis vectors with many-body configurations, and compare the physical properties of the resulting Hamiltonians. We characterize the scaling of the many-body eigenstate entanglement entropy with system size for the different labeling schemes and in each of the phases. Using a scaling analysis on the full sets of eigenstates, we subsequently provide a quantitative picture of the boundary between the different types of scaling behavior that we observe for the spectral-bulk and spectral-edge eigenstates. Reference: W. Buijsman, M. Haque, and I.M. Khaymovich, arXiv:2503.08825 (2025).

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