Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 14: Many-Body Quantum Dynamics 2 (joint session DY/TT)
TT 14.5: Vortrag
Dienstag, 6. September 2022, 12:30–12:45, H20
Effect of electron-electron interaction on the spectral statistics in circular sector graphene billiards — •Xianzhang Chen1,2 and Liang Huang1 — 1Lanzhou Center for Theoretical Physics, and Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou, Gansu 730000, China — 2Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
The spectral statistics is a fundamental issue in quantum chaos and has been used widely as a measure to probe the complexity of the underlying quantum systems. In this work, we adopt the one-orbital mean-field Hubbard model to investigate the effect of many-body interactions on the spectral statistics of circular sector graphene billiards. It is found that the spectral statistics are insensitive to the Hubbard interaction U for most of the energy ranges, except for energies around the Dirac point. We choose two representative systems, whose spectral statistics follow Poisson and Gaussian orthogonal ensemble (GOE) when U=0, respectively. As U increases, for both cases, the spectral statistics moves toward GOE. However, after passing a critical value Uc, the spectral statistics turns back toward Poisson as U is increased further, due to the emerging gap and henceforth distinct behaviors of the quasiparticles. In addition, the energies above and below the Dirac point may exhibit different spectral statistics. These results uncover the intriguing connection between Hubbard interaction and the spectral statistics in graphene sector billiards. A physical picture is provided to understand these effects.