题 目：Multi-fermion-clustering ordering

报告人：吴从军 教授，西湖大学

邀请人：徐刚教授、姚凯伦教授

时 间：2023年5月7日（周日）上午10:00

地 点：国家脉冲强磁场科学中心B206会议室

报告摘要：

Typical mean-field theories for many-body states rely on two-fermion orderings. Order parameters lie in either the particle-particle channel such as pairing orders for superconductivity, or, in the particle-hole channel such as spin-density-wave orders for antiferromagnetism. Nevertheless, in high energy quantum chromodynamics, three quarks form a colorless baryon, and in nuclear physics, two protons and two neutrons form a spin and isospin singletα-particle. We examine this class of multi-particle fermion multi-particle clustering instabilities in one-dimensional spin-3/2 fermion systems via the renormalization group and bosonization method, which exhibit the quartetting superfluidity (charge 4e) and quartet density wave orderings. For a two-band superconductivity, we identify a normal state with a two-particle-two-hole type ordering exhibiting time-reversal symmetry breaking as a consequence of strong phase fluctuations. We also introduce a mechanism of the charge-6e state via frustration of pair-density-wave state, which may be relevant to the recent hc/6e oscillations observed in the Little-parks type experiments in Kagome superconductors.

参考文献：

[1] Yu-Bo Liu, Jing Zhou, Congjun Wu, Fan Yang Charge 4e superconductivity and chiral metal in the 45∘-twisted bilayer cuprates and similar materials，arXiv:2301.06357 .

[2] Zhiming Pan, Chen Lu, Fan Yang, Congjun Wu, Frustrated superconductivity and "charge-6e" ordering，arXiv:2209.13745 .

[3] Meng Zeng, Lun-hui Hu, Hong-Ye Hu, Yi-Zhuang You Congjun Wu, Phase-fluctuation Induced Time-Reversal Symmetry Breaking Normal State, arXiv:2102.06158 .

[4] Congjun Wu, "Competing orders in one dimensional spin 3/2 fermionic systems", Phys. Rev. Lett. 95, 266404 (2005) .

[5] F. Hubert, Zi Cai, V. G. Rousseau, Congjun Wu, R. T. Scalettar, G. G. Batrouni, Exotic phases of interacting p-band bosons“, Phys. Rev. B 87, 224505 (2013) .

报告人简介：

Congjun Wu received his Ph.D. in physics from Stanford University in 2005, and did his postdoctoral research at the Kavli Institute for Theoretical Physics, University of California, Santa Barbara, from 2005 to 2007. He became an Assistant Professor in the Department of Physics at the University of California, San Diego in 2007, an Associate Professor in 2011, and a Professor in 2017. In 2021, he became a Chair Professor at School of Science, Westlake University. He was selected as a New Cornerstone Investigator in 2023, elected to a Fellow of American Physical Society in 2018, and awarded the Sloan Research fellowship in 2008. His research interests are exploring new states of matter and reveling their organizing principles, including quantum magnetism, superconductivity, topological states, mathematical physics, and the numerical method of quantum Monte Carlo simulations.