报告时间：2015年6月18号（周四）下午4:20

报告地点：物理学院新楼5多功能厅

报告人：游建强教授（北京计算科学研究中心）

摘要：

A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external a.c. electric field, an effect called electric-dipole spin resonance. Here we develop a theory that can be applied in the strong SOC regime. We find that there is an optimal SOC strength, where the Rabi frequency induced by the a.c. electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. In addition, our study is extended to a semiconductor nanowire double quantum dot with strong SOC. We show that both spin-conserved and spin-flipped tunnelings exist and they can compete with each other when increasing the SOC. Moreover, strong Coulomb repulsion in the nanowire double quantum dot can be combined with the SOC-dependent tunnelings to yield an anisotropic exchange coupling between the two spin-orbit qubits. Furthermore, we give an explicit physical picture for this anisotropic exchange coupling.

报告人简介：

游建强教授现为北京计算科学研究中心讲座教授，量子物理与量子信息研究部主任，主要从事量子信息和凝聚态物理的研究。1984年毕业于湘潭大学物理系，获学士学位；1988年毕业于中国科学院金属研究所，获硕士学位；1997年毕业于中国科学院固体物理研究所，获博士学位。曾任复旦大学物理系谢希德冠名教授，曾获日本理化学研究所前沿研究头等奖、安徽省自然科学二等奖和中国科学院院长奖学金特别奖。

邀请人：张文献教授