Correlation-Induced Insulating Topological Phases at Charge Neutrality in Twisted Bilayer Graphene

Twisted bilayer graphene (TBG) consists of two stacked layers of graphene rotated relative to one another. With a twist angle of about 1.10° the so-called “magic” angle, many unconventional electronic behaviors emerge, including superconductivity and correlated insulators, a type of insulating phase that arises from interactions between electrons. Elucidating the mechanism responsible for these electronic states in magic-angle TBG is a problem at the frontier of quantum materials research. To help solve this problem, we employ an unbiased quantum many-body numerical method (quantum Monte Carlo simulations) to investigate the possible insulating phases of TBG.

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The search of non-Fermi liquid

Three passions, simple but overwhelmingly strong, have governed my life: the longing for love, the search of knowledge, and unbearable pity for the suffering of mankind.

—Bertrand Russell

As Russell nicely put it, scientists are often driven by strong passions for the search of knowledge, such search not only benefits the human society, but often times brings the ecstasy to themselves -- the ecstasy for instance of understanding the hearts of men, knowing why the stars shine, and apprehending the Pythagorean power by which number holds sway above the flux -- that is so great that scientists would often have endured the long hours of working and sleepless nights for the pursuit of such joy. Continue reading "The search of non-Fermi liquid"

DQMC Note (行列式蒙卡之我见)

        这些笔记是潘高培君学习行列式量子蒙特卡洛方法(Determinantal Quantum Monte Carlo, DQMC)中总结出的心得。基本描述了 DQMC 实现过程。内容主要参考了 Fakher Assaad 等人的综述文章和组里几位学生的笔记,按照笔者自己喜欢的逻辑顺序进行讲述,顺便补充了少数被略过的推导。希望可以作为一个行列式蒙卡学习中的参考资料。欢迎大家批评指正。

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神州帽子何其多

在一段悠然慵懒的岁月里,作者一边进行量子蒙特卡洛计算,一边读着二十四史。在量子多体中的呐喊与彷徨中看到了一丝曙光,也在历史的回味与反思中看到当今科研体制下的无奈与坚忍。“学者的贡献在于发扬真理,脱心志于俗谛之桎梏,在于铸造后起的头脑,不在于自己头上有多少帽子。” Continue reading "神州帽子何其多"

Quantum Material research connecting physicists in Hong Kong, Beijing and Shanghai

A joint research team from The University of Hong Kong (HKU), Institute of Physics at Chinese Academy of Science, Songshan Lake Materials Laboratory, Beihang University in Beijing and Fudan University in Shanghai, provide a successful example of modern era quantum material research. Continue reading "Quantum Material research connecting physicists in Hong Kong, Beijing and Shanghai"

Breakthrough in Understanding Quantum Metals

Metals, especially interacting metallic states, never stop surprising people. Among the interesting phenomena that have emerged is the “high-temperature” superconductivity. This holds great promise for enabling highly-efficient energy transportation, but it can be achieved only at extremely cold temperatures (about -100 degrees Celsius or below) that are currently too costly and energy-intensive to replicate. Continue reading "Breakthrough in Understanding Quantum Metals"

历史的终结与最后的人

稍微熟悉一些政治理论的朋友应该都知道弗朗西斯·福山 (Francis Fukuyama)的这本书《历史的终结与最后的人》(The End of History and the Last Man),此书成于1990年代初,就着当时的时代背景(东欧巨变、苏联解体、冷战结束)预言了人类社会最终的组织形式将会是 liberal democracy。福山先生放眼人类历史上下几千年,剖析波澜壮阔的20世纪,师承从康德、黑格尔到马克思的德国古典哲学与人类社会发展阶段理论,提出“历史终结论”。Continue reading

一生能有多少爱

我承认,这是一个俗气的题目。

很多年前,大概是还觉得《读者》之类的鸡汤文字集合是文学的时候吧,不知在什么地方见到过以此为题目的一本书。内容自然记不清楚了,大抵都是些content-free 的大实话:人生艰难,痛苦总是多于欢欣,没有爱的扶持我们怎么能够坚持下去云云。时过境迁,已经练就了铁石心肠鸡汤不入,只有这个题目还映在脑海里。Continue reading

​金属的油腻表叔:一个没有电子费米面的新金属态 | 众妙之门

幸福的家庭都是相似的,不幸的家庭各有各的不幸。作家通过文学作品刻画人类社会的光怪陆离,科学家通过研究探索物质世界的丰富现象。这不,很多年前学界中传言金属家族中其实还有一位人们从未谋面的邋遢表叔—— “正交金属”。Continue reading