Non-ergodic extended states in $\beta$-ensemble

• URL: http://arxiv.org/abs/2112.11910v2
• Date: Wed, 20 Apr 2022 15:24:44 GMT
• Title: Non-ergodic extended states in $\beta$-ensemble
• Authors: Adway Kumar Das and Anandamohan Ghosh
• Abstract summary: We numerically study the eigenvector properties of $beta$-ensemble. We find that the chaotic-integrable transition coincides with the breaking of ergodicity in $beta$-ensemble but with the localization transition in the RPE or the 1-D disordered spin-1/2 Heisenberg model.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Matrix models showing chaotic-integrable transition in the spectral statistics are important for understanding Many Body Localization (MBL) in physical systems. One such example is the $\beta$-ensemble, known for its structural simplicity. However, eigenvector properties of $\beta$-ensemble remain largely unexplored, despite energy level correlations being thoroughly studied. In this work we numerically study the eigenvector properties of $\beta$-ensemble and find that the Anderson transition occurs at $\gamma = 1$ and ergodicity breaks down at $\gamma = 0$ if we express the repulsion parameter as $\beta = N^{-\gamma}$. Thus other than Rosenzweig-Porter ensemble (RPE), $\beta$-ensemble is another example where Non-Ergodic Extended (NEE) states are observed over a finite interval of parameter values ($0 < \gamma < 1$). We find that the chaotic-integrable transition coincides with the breaking of ergodicity in $\beta$-ensemble but with the localization transition in the RPE or the 1-D disordered spin-1/2 Heisenberg model where this coincidence occurs at the localization transition. As a result, the dynamical time-scales in the NEE regime of $\beta$-ensemble behave differently than the later models.

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