时间：5月22日（周五）下午14:00

地点：勤园 20-518

报告简介：

BCS theory fails to explain the pseudogap in cuprate superconductors, which likely arise from stronger pairing interactions than in conventional superconductors. Strong pairing leads to significant contributions from non-condensed fermion pairs, resulting in a pseudogap in the single-particle excitation spectrum. Such systems lie in the crossover between BCS superconductivity and Bose-Einstein condensation (BEC). This talk presents a pairing fluctuation theory that consistently incorporates both zero-momentum coherent Cooper pairs and finite-momentum incoherent pairs into the fermion self-energy. The latter naturally gives rise to a pseudogap both above and below Tc when pairing is strong. The theory applies to s-wave and d-wave superconductors as well as neutral superfluids in ultracold atomic Fermi gases, where the pairing strength is tunable via Feshbach resonance. Experimental evidence supporting such strong-pairing superfluids is discussed, along with predictions of exotic quantum phenomena, including pair-density-wave ground states and ultrahigh-temperature superfluidity emerging in population-imbalanced optical lattices in one and two dimensions.

报告人简介：

陈启瑾，中国科学技术大学讲席教授、合肥国家实验室高级研究员、教育部长江学者。1992年本科毕业于中科大，2000年获芝加哥大学博士，先后在美国国家强磁场实验室、约翰斯·霍普金斯大学及芝加哥大学从事理论研究。回国后曾任职于浙江大学。长期从事凝聚态理论与冷原子气体研究，聚焦高温超导赝能隙及超冷费米气体中的配对涨落、BCS-BEC渡越、量子多体效应等前沿课题。他发展的配对涨落理论成功定量解释了多项高温超导实验现象，并首次将赝能隙概念引入费米冷原子超流体系，在热力学相变、射频谱理论等方面取得重要成果，预言了若干新奇量子现象。已在Science、Nature、Reviews of Modern Physics、Physics Reports（应邀撰写费米冷原子气体领域首篇综述）、Physical Review Letters等期刊发表论文100篇，Google Scholar总引用4800余次，H指数36。目前主持国家科技创新2030重大研究项目理论课题，聚焦于高温超导的机理研究，发展超越现有模型的新理论，为实验提供指导。