百望讲坛

◆ 第17期 ◆

【时间】2022年1月12日（周三） 上午10:00
       【地点】量子院320报告厅

【报告人】孙昌璞  中国工程物理研究院研究生院院长，北京计算科学研究中心教授

【主持人】徐洪起  量子院量子计算研究部执行部长

【题目】超导-半导体纳米线异质系统中的Majorana零模：理论与实验

【摘要】 The hybrid nanowire consisting of semiconductor with proximity to superconductor is expected to serve as an experimental platform to display Majorana zero modes. By rederiving its effective Kitaev model with spins, we discover a novel topological phase diagram, which assigns a more precise constraint on the magnetic field strength for the emergence of Majorana zero modes. It then turns out the effective pairing strength dressed by proximity effect exhibits a significant dependence on magnetic field, and thus the topological phase region is refined as a closed triangle in the phase diagram with chemical potential vs. Zeeman energy (which is obviously different from the open hyperbolic region known before). This prediction is confirmed again by an exact calculation of quantum transport, where the zero bias peak of 2e²/h in the differential conductance spectrum, as the necessary evidence for the Majorana zero modes, disappears when the magnetic field grows too strong. For illustrations with practical hybrid systems, in the InSb nanowire coupled to NbTiN, the accessible magnetic field range is around 0.1?1.5 T; when coupled to aluminum shell, the accessible magnetic field range should be smaller than 0.12 T. These predictions obviously clarify the current controversial issues about some experiments of Majorana zero modes with hybrid nonawire .  

【报告人简介】 孙昌璞，理论物理学家，中国科学院院士，发展中国家科学院院士，中国工程物理研究院研究生院院长，北京计算科学研究中心教授。主要从事量子物理、数学物理和量子信息理论研究。1962年7月生于辽宁省普兰店市。1984年毕业于东北师范大学物理系，1987年于该校获得硕士学位，1992年于南开大学获博士学位。2009年当选为中国科学院院士。