报告题目：Potential valley Qubit: Brightened dark excitons in transition metal dichacogenide monolayers
报告人：屈凡尧教授 巴西利亚大学
报告时间：2018年12月28日星期五14：00
报告地点：长清湖校区文澜楼A347
报告摘要：
Exploiting the “valley” degree of freedom to store and manipulate information is an emerging direction of condensed matter physics, which might provide a novel paradigm for future electronics. Monolayer transition metal dichalcogenides (TMDs) feature valley-dependent optical selection rules and spin–valley locking effect. The former allows for the convenient creation, manipulation and detection of excitons in specific valleys with circularly polarized light and the latter suggests a very long spin–valley lifetime. However, recent experimental data shows that the spin–valley lifetime of bright excitons in the TMD monolayers is rather short. This reduced lifetime of the bright excitons limits their use as spin or valley qubits. We theoretically investigate the valley dynamics and steady state emissions of multiexcitons in monolayer WS2 subjected to a tilted magnetic field. We demonstrate that the dark excitons can be efficiently brightened. Both brightened dark excitons and biexcitons exhibit large valley splittings; nevertheless, the former is twice as large as the latter. Besides, their magneto-photoluminecence display very strong valley anisotropy. Therefore the dark exciton in the TMDs can be used as potential valley Qubit due to its long spin-valley lifetime and large valley splitting.
报告人简介：
屈凡尧现任巴西利亚大学物理系教授，曾先后在曲阜师范大学物理系、加州大学伯克利分校物理系、加拿大科学院、巴西乌伯兰迪亚联邦大学、意大利国际理论物理研究中心和德克萨斯大学奥斯汀分校任职或访学。研究兴趣包括：二维材料和范德瓦尔斯异质结的电子结构、光热、量子输运及拓扑性质，范德瓦尔斯异质结的自旋和多激子的谷动力学，量子信息和纳米器件模拟，等。先后在Phys. Rev. Lett., Phys. Rev. B和Appl. Phys. Lett等主流物理期刊发表论文近百篇，参与《Quantum-dot Based Light-emitting Diodes》等4部专著的编纂，在国际大会做邀请报告19次，并组织国际会议2次。
