The research team developed a new and more efficient quantum algorithm of the Monte Carlo techniques adopted by scientists to measure the Renyi entanglement entropy of objects. With this new tool, they measured the Rényi entanglement entropy at the DQCP and found the scaling behaviour of the entropy, i.e. how the entropy changes with the system sizes, is in sharp contrast with the description of conventional LGW types of phase transitions. Continue reading

In the time of quantum technology and big data, scientists start to integrate Artificial Intelligence (AI) and computational approaches into the fundament research about our mother Nature and Universe. This series of two lectures will help us to unfold such interesting discovery processes. Dr Zi Yang MENG, Associate Professor at HKU Department of Physics, will explain the important role played by AI and computation in the modern quantum material research in the first lecture. Find more

Imagestacking two sheets of graphene – the 2D form of graphite, or the pencil at your hand – in which the carbon atoms form a hexagonal lattice and twist the top sheet out of alignment with the sheet below, yielding a periodic arrangement of atoms named moiré pattern. Do you know that at a twisted angle of about 1^o – people now call it the ‘magic’ angle – the system could exhibit very exotic behaviours such as becoming an insulator, a metal or even a superconductor? Can you imagine the same carbon atom in your pencil (graphite) becoming a superconductor when twisted to the magic angle? It indeed did as people discovered it in 2018, but why? Continue reading

The Higgs mode or the Anderson-Higgs mechanism (named after another Nobel Laureate Philip W ANDERSON), has widespread influence in our current understanding of the physical law for mass ranging from particle physics - the elusive “God particle” Higgs boson discovered in 2012 to the more familiar and important phenomena of superconductors and magnets in condensed matter physics and quantum material research. Continue reading

发明量子多体问题算法的人，多与普通人不同。他们身上有一种得道高僧、终南隐士的先知之气，往往想要扬弃和重新评价流俗所看重的种种价值观念，率性而为以至于不被社会所理解，甚至被视为狂士和疯子。这其中的原因，恐怕还是来自于在量子多体问题中发明算法本身的难度。Continue reading

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. Continue reading

Quantum materials are becoming the cornerstone for the continuous prosperity of human society, including the next-generation AI computing chips that go beyond Moore’s law, the high-speed Maglev train, and the topological unit for quantum computers, etc. However, these complicated systems require modern computational techniques and advanced analysis to reveal their microscopic mechanism. Continue reading

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