报告人：

刘雄军

报告人单位：

北京大学量子材料中心

报告时间：

3月28日下午 15:00

报告地点：

科技楼，北楼410会议室

邀请单位：

凝聚态物理研究所

报告摘要：

Topological superconductors, which host Majorana zero modes, are a most attractive research topic in condensed matter physics. Due to the Kramers theorem, in a time-reversal invariant topological superconductor the Majroana modes come in pairs, called Majorana Kramer pairs (MKPs). The recent study showed that, due to the time-reversal symmetry protection, the MKPs may obey non-Abelian braiding statistics, while it was later pointed out that local rotation among a single MKP may cause errors in MKP-based qubits. In the work presented in this talk, I shall show complete symmetry condition for non-Abelian braiding of MKPs. By introducing an effective Hamiltonian approach to describe the braiding of MKPs, we show that the ideal non-Abelian braiding is protected when the effective Hamiltonian exhibits a new time-reversal like anti-unitary symmetry, which is satisfied if the system is free of dynamical noise. On the other hand, the presence of dynamical noise may bring about decoherence only when the correlation function of such noise breaks the time-reversal like symmetry in the time domain. Interestingly, the resulted error is found to be a higher order effect, compared with the decoherence of Majorana qubits without time-reversal symmetry protection, caused by the dynamical perturbations. These results show that the non-Abelian braiding of MKPs is observable and may have versatile applications to future quantum computation technologies.

报告人简介：

刘雄军教授2011年于德州A&M大学取得博士学位，2011年到2014先后在马里兰大学Joint Quantum Institute和凝聚态理论中心，香港科大高等研究院以及麻省理工学院从事博士后研究。2014年加入北京大学量子材料中心担任研究员。他的主要研究方向涵盖凝聚态理论和冷原子物理，并集中在量子物质拓扑相，Majorana fermion，人工自旋轨道耦合和规范场等方面。目前发表文章近40篇，主要发表在PRL，PRX，Nature子刊系列等杂志。