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arXiv · 2607.01888

Interaction-rotation driven localization-delocalization crossover in Fock space: An exact diagonalization study on trapped Bose gas

Mohd Talib·M. A. H. Ahsan
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Abstract

We study the localization-delocalization crossover and quantum entanglement with varying numbers of interacting bosons for the nonrotating and the rotating cases. The many-body ground state within subspaces of given total angular momentum is obtained via exact diagonalization and analyzed using the inverse participation ratio (IPR), the information (Shannon) entropy and the von Neumann entanglement entropy. In the non-rotating case, a crossover from localization to delocalization is observed with increasing interaction, characterized by decreasing value of IPR with corresponding increase in information entropy and von Neumann entanglement entropy, arising from interaction-induced depletion of Bose-Einstein condensate. When subjected to rotation, the system is driven further towards delocalization due to rotation-induced depletion of Bose-Einstein condensate. The crossover from localization to delocalization is indicated by distribution of the eigenstate weights over an increasing number of basis states in the many-body Hilbert space. The consistent behavior of IPR, information entropy and von Neumann entanglement entropy with respect to interaction and rotation demonstrates that these quantities provide a unified characterization of the localization-delocalization crossover. Results on computed von Neumann entropy show that localized states exhibit weak entanglement while delocalized states are characterized by strong entanglement within the quantum many-body system.

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Mohd Talib, M. A. H. Ahsan. 2026-09-15. Interaction-rotation driven localization-delocalization crossover in Fock space: An exact diagonalization study on trapped Bose gas. https://arxiv.org/abs/2607.01888

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