Bye, Mr. Zhang

Congratulations from Zi Yang:

August 6, 2024, is a significant day for Mr. Xu Zhang, as on this day he has successfully defended his Ph.D. thesis with the title “Electromagnetic response in two dimensional flat band systems”. He has greatly impressed the Examining Committee comprised of Profs. Xi Dai and Ning Wang from HKUST and Profs. Wang Yao and Dong-Keun Ki from HKU, in clearly presenting the major research outputs during his Phd years in HKU, as well as addressing the interesting questions spontaneously appeared during the defense. Congratulations to Dr. Xu Zhang! And hope him a successful next step and becomes the next rising star in theoretical condensed matter physics. Continue reading

Unlock Tunable Nonlinear Hall Effect in Twisted Bilayer Graphene

A team of international researchers led by HKU (composed of PhD student Xu ZHANG and his advisor Dr Zi Yang MENG) and HKUST has made a significant discovery in the field of quantum materials, uncovering the controllable nonlinear Hall effect in twisted bilayer graphene. The findings, published as an Editors' Suggestion article in the prestigious physics journal Physical Review Letters, discovered that by adjusting the dispersion of the topological flat bands in twisted bilayer graphene, the Berry curvature dipole moments, which play a crucial role in the Hall effect, can be easily controlled and manipulated. Continue reading

阿龙探案蒙特卡洛符号问题

量子多体计算领域有几个传统的谜团或者说神话故事,比如量子蒙特卡洛计算一旦遇到符号问题,其重要性抽样就当场失效;比如张量网络计算总能克服万难成功找到指数大的希尔伯特空间中那个甜蜜的小角落;比如第一性原理计算得到的能带可以煞有介事地解释关联电子材料的能谱;……。既然是谜团,就是可以没有标准答案,从业人员信与不信全看当时的心情,或者想也不想,别人怎么说我也怎么说。几十年过去了,谜团或者说神话故事,就这么口口相传下来。但是总有愿意琢磨事儿的人 ...... Continue reading

   

库伦作用无尽期,动量蒙卡寄相思

白石道人姜夔,南宋词人,一生布衣游食四方,存词只有80余首,不算高产(虽然他21岁写下的《扬州慢·淮左名都》入选中学语文课本,诸君可以想想自己21岁时在做什么)。但在他43岁那年的正月里,情感不知为何受到了大的扰动,爆发似的一口气写下一组五首《鹧鸪天》(准确地说是从正月初一到正月十六,从第一首《鹧鸪天 • 丁巳元日》到第五首 《鹧鸪天 • 十六夜出》),曲折地追怀自己生命中一段年轻的爱情,五首皆为精品。 Continue reading