报告摘要:

In the realm of condensed matter physics, the fractional quantum Hall effect stands as a singular experimental manifestation of topological order, characterized by the presence of anyons—quasiparticles that bear fractional charge and exhibit exchange statistics diverging from conventional fermions and bosons. This phenomenon, observed over four decades ago, was still missing the direct observation of similar topological orders arising purely from band structure—without the application of strong magnetic fields. In 2023 within the span of a few months, several pioneering experiments have illuminated this once theoretical domain. Studies on twisted homobilayer MoTe₂and pentalayer rhombohedral graphene placed on hBN have finally unveiled the existence of fractional Chern insulators (FCIs), the zero-magnetic field analog of fractional quantum Hall states.

The journey to this point, preceded by over a decade of theoretical frameworks and predictions surrounding FCIs, yet the experimental revelations have proved to be richer and more surprising than expected. In this talk, we will present how the combination of ab-initio and quantum many-body calculations can help us capture the different features observed in experiments. We will discuss the potential future for this exciting booming field, including the possible observation of fractional topological insulators, a yet-never observed topological ordered phase preserving the time reversal symmetry.

报告人简介：

Nicolas Regnault，2001年获XI奥赛大学/CEA-Saclay物理研究所博士学位，随后在Niall Moran从事博士后研究。先后担任Université Paris VI助理教授及普林斯顿大学客座研究员，2023年起任巴黎高等师范学院的CNRS研究主任。曾获得巴黎高等师范学院“Habillitation à Diriger des Recherche”和 CNRS铜牌勋章。他在博士期间进行引力可积模型的相关研究，后转向凝聚态物理方向，是分数量子霍尔效应研究领域著名专家，尤其关注物质的拓扑相、多体量子态和非平衡量子系统中的纠缠特性等方向。发表包括Nature，Physical Review Letters等在内的论文200余篇，累计被引11000余次，单篇最高引用近1000次。其受邀在国际会议进行60余次报告，曾作为合作者主办“Moiré in Paris”等多个物理学术会议。

主要代表性成果：

[1]Kevin P. Nuckolls, Ryan L. Lee, Myungchul Oh, Dillon Wong, Tomohiro Soejima, Jung Pyo Hong, Dumitru Călugăru, Jonah Herzog-Arbeitman, B. Andrei Bernevig, Kenji Watanabe, Takashi Taniguchi, Nicolas Regnault, Michael P. Zaletel & Ali Yazdani. Quantum textures of the many-body wavefunctions in magic-angle graphene.Nature620, 525–532 (2023).

[2] B. J. Wieder, B. Bradlyn, J. Cano, Zhijun Wang, M. G. Vergniory, L. Elcoro, A. A. Soluyanov, C. Felser, T. Neupert, N. Regnault, B. A. Bernevig. Topological materials discovery from crystal symmetry.Nature Reviews Materials7, 196 (2022).

[3]S Moudgalya, S Rachel, BA Bernevig, N Regnault.Exact excited states of nonintegrable models.Physical Review B98 (23), 235155 (2018).

[4] N Regnault, BA Bernevig. Fractional Chern insulator.Physical Review X1 (2), 021014 (2011).

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