报告人：

徐刚 教授

报告人单位：

斯坦福大学

报告时间：

3月29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：

Dr. Gang Xu got his PHD in the institute of physics (IOP), CAS in 2010. From 2010 to 2015, Gang worked as an assistant and associate researcher in IOP. Since November 2012, Gang visit Shou-Cheng Zhang’s group as a postdoc in Stanford University. My main studies are focus on the electronic structures and physical properties calculated by the first principles calculations and the condensed matter theory. Until now, Gang has published more than 30 papers on the high level international journals, including 7 in PRL, 2 in Nature Nanotechnology, 1 in Nature communication and 2 in Nano letters. Total citations are more than 2600. H-index=20.