报告人：Jian Huang (Wayne State University)

时间地点：2023年10月11日周三下午3:00，理科楼C302

报告摘要：Topology provides an important concept for achieving dissipationless states that are key to sustaining unchanged quantum electron properties to remarkable precisions [1,2]. So far, most understanding of the protection mechanism comes from edge-state studies in light of (disorder) scattering effects. However, the available results do not adequately explain the ubiquitously system-dependent and variable robustness levels [3]. This study investigates reconstructive situations where protected dissipationless modes become global instead of restricted to the sample edge. This is realized in the integer quantum Hall effect (IQHE) hosted in a Corbino sample geometry [4] brought to the verge of a breakdown. Detection of the onset of dissipation is made simultaneously in both longitudinal and transverse directions with two independent measurement setups, one along the sample edge and the other across the bulk. The real-time correspondence between results in orthogonal directions confirms perfectly maintained topology even when the dissipationless charge modes become dynamically reconfigurable on global scales. A breakdown mechanism is also revealed as resonances causing backscattering between these reconfigurable dissipationless current paths bridging opposite sample edges. The enhanced protection is beyond the bare disorder effect and is qualitatively explainable by impurity screening arising from electron-electron interaction. These findings should provide insights to explain the discrepancies in the robustness levels [5,6] and a means for optimization.

[1] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).

[2] X.-L. Qi and S.-C. Zhang, Rev. Mod. Phys. 83, 1057 (2011).

[3] A. Tzalenchuk, S. Lara-Avila, A. Kalaboukhov, et al., Nat. Nanotech. 5, 186 (2010).

[4] B. I. Halperin, Phys. Rev. B 25, 2185 (1982).

[5] A. Marguerite, J. Birkbeck, A. Aharon-Steinberg, et al., Nature 575, 628 (2019).

[6] N. Moreau, B. Brun, S. Somanchi, et al., Nat. Commun. 12, 4265 (2021).

报告人简介：Jian Huang is a professor in the Department of Physics and Astronomy at Wayne State University. He received his B.S. in physics from Peking University, M.S. in theoretical physics from University of South Carolina under Professors James Knight and Yakir Aharonov, and Ph.D. in experimental physics from Michigan State University under Professor Norman Birge. After a short postdoctoral stint at NIST in Boulder, Colorado, he joined Dan Tsui's group at Princeton University as a postdoc. His research interest lies in quantum mechanical phenomena in electron systems subject to strong electron-electron correlation.