Recent research demystifies the effects of long-range interactions on physical systems. Our quantum Monte Carlo simulations and field theoretical analysis on (2+1)-dimensional O(3) quantum critical points and two-dimensional Néel states with long-range interactions have uncovered the critical exponents of quantum critical points influenced by long-range interactions exhibit three distinct renormalization group fixed points (Phys. Rev. B 109, L081114 (2024) Editor's suggestion). At finite temperature, our unbiased investigation demonstrated the spontaneous breaking of SU(2) symmetry in Heisenberg model with 1/r^α-form long-range interactions beyond the Mermin-Wagner theorem. Critical exponents have been determined for different ranges of α, revealing new critical behaviors (npj Quantum Mater. 8, 59 (2023)). These works encourage further theoretical and experimental studies of quantum materials with long-range interactions, expanding our understanding beyond locality.

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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

August 18, 2023, is a significant day for Mr. Jiarui Zhao and Mr. Chengkang Zhou, as on this day they have successfully defended their Ph.D. thesis with the title “Disorder Operators, Entanglement Entropies, and Dynamic Spectra in Strongly Correlated Quantum Spin Systems：A Quantum Monte Carlo Study” and “Quantum Monte Carlo simulations of dimension tunability phenomena in the quantum spin system”. They are the first-generation HKU PhD graduates from Zi Yang Meng’s group. Congratulations to Dr. Jiarui Zhao and Dr. Chengkang Zhou! Continue reading

To pursue advances in astronomy, quantum physics, and interdisciplinary science, our research teams worked together to deploy a new supercomputing system, named ‘Blackbody’ supercomputer -- the name stems from their respective research topics of ‘Black hole’ and ‘Quantum many-body‘ physics. The system has been set up in fall 2022 and is currently in full operation. Thank you for the hard work and Congratulations for all the participants! Continue reading

Quantum dimer models are known to host topological quantum spin liquid phases, and it has recently become possible to simulate such models with Rydberg atoms trapped in arrays of optical tweezers. By means of large-scale quantum Monte Carlo simulations ... we find distinct odd and even Z2 spin liquids, along with several phases with no topological order: a staggered crystal, a nematic phase, and a trivial symmetric phase with no obvious broken symmetry. We also present dynamic spectra of the phases, and note implications for experiments on Rydberg atoms. Continue reading