# 量子论坛：Chiral transport in a topological material/superconductor hybrid

**量子论坛第二十六讲**

**报告题目：**Chiral transport in a topological material/superconductor hybrid

**报告人: **Chao Zhang, Senior Professor, School of Physics, University of Wollongong, NSW, Australia

**报告时间: **4月20上午10:00

**报告地点: **量子楼409报告厅

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**报告摘要: **We
demonstrate some interesting chiral transport phenomena in a
topological material/superconductor hybrid. (1) Specular Andreev
reflection (SAR) can occur in semiconductors where the spin-orbit
coupling is finite. In a hybrid of a two-dimensional electron gas with
Rashba spin-orbit coupling and a superconductor and in the limit of low
density or a strong spin-orbit coupling, specular Andreev reflection is
finite. We show that unit electron-hole conversion is possible in a
specular Andreev reflection due to the different topological structures
of the equal-energy surface between electrons and holes. The SAR in the
semiconductor is determined by the relative orientation of wave vector
to group velocity, which can be analyzed by ray equations. (2) Electrons
can undergo retro-reflection in bilayer graphene (BLG)/superconductor
hybrid. The underlying mechanism for this previously unknown process is
the anisotropic constant energy band contour of BLG. The electron group
velocity is fully reversed upon reflection, causing electrons to be
retro-reflected. (3) Strong spin-orbit coupling can result in a quantum
ratchet effect.

**报告人简历**:
Professor Chao Zhang received his PhD in physics in 1987 from City
University of New York, USA. From 1987 to 1989, he was a postdoctoral
fellow at Max-Planck-Institute for Solid Research in Stuttgart, Germany,
working on quantum magneto-transport in semiconductor nanostructures.
From 1989 to 1992, He was a research associate at Canada’s Meson
Research Facility in Vancouver, working on quantum coherence and
dissipation in solids. From 1993, he has been a tenured faculty member
in the School of Physics, University of Wollongong, Australia. Currently
he is a senior professor of physics. From 2004-2014, he served as the
associate director of the Institute of Superconducting and Electronic
Materials. He is a Fellow of Australian Institute of Physics. He is the
associate editor of Frontier of Optolelectronics and a member of the
editorial board of Scientific Report. His research interest is in the
areas of quantum transport of nanostructures, terahertz photonics,
nonlinear dynamics of semiconductors, graphene and topological
insulators. He has published around 200 papers in refereed journals with
an H-index of 30. He has received many awards including Norwegian
Research Council Fellowship (1990), Norwegian Research Council Senior
visiting fellowship (1996), JSPS senior fellowship (2002), and
Australian Academy of Science International Award (2000, 2004).