近日，中国科学技术大学的潘建伟&姚星灿&陈宇翱及其研究团队取得一项新进展。经过不懈努力，他们实现幺正费米气体中赝能隙的观测和定量化。相关研究成果已于2024年2月7日在国际权威学术期刊《自然》上发表。
该研究团队报道了利用动量分辨微波光谱技术，精准测量了费米子谱函数。在排除了终态相互作用的虚假效应后，研究人员在均匀的锂-6原子幺正费米气体中观察到了由配对波动驱动的赝能隙。通过光谱分析，研究人员定量确定了配对能隙、逆配对寿命和单粒子散射率与温度的关系。值得注意的是，在超流体转变温度之上，他们发现了显著的赝能隙存在。
此外，逆配对寿命呈现热激活指数行为，揭示了微观层面上的虚拟配对破缺与复合机制。所得到的单粒子散射率与普朗克极限所设定的散射率相当，且几乎不随温度变化。这一研究定量描述了强相互作用费米气体中的赝能隙现象，并有力支持了预形成配对作为超流动性前兆的观点。
据悉，铜酸盐高温超导性的微观起源仍然是未知的。人们普遍认为，通过更好地了解铜酸盐的正常非超导态赝能隙相，可以取得实质性的进展。特别是，一个核心问题是赝能隙是否可能源于强配对波动。在幺正费米气体中，赝能隙(如果存在的话)必然是由多体配对产生的，它提供了理想的量子模拟器来解决这个问题。
附：英文原文
Title: Observation and quantification of the pseudogap in unitary Fermi gases
Author: Li, Xi, Wang, Shuai, Luo, Xiang, Zhou, Yu-Yang, Xie, Ke, Shen, Hong-Chi, Nie, Yu-Zhao, Chen, Qijin, Hu, Hui, Chen, Yu-Ao, Yao, Xing-Can, Pan, Jian-Wei
Issue&Volume: 2024-02-07
Abstract: The microscopic origin of high-temperature superconductivity in cuprates remains unknown. It is widely believed that substantial progress could be achieved by better understanding of the pseudogap phase, a normal non-superconducting state of cuprates. In particular, a central issue is whether the pseudogap could originate from strong pairing fluctuations. Unitary Fermi gases, in which the pseudogap—if it exists—necessarily arises from many-body pairing, offer ideal quantum simulators to address this question. Here we report the observation of a pair-fluctuation-driven pseudogap in homogeneous unitary Fermi gases of lithium-6 atoms, by precisely measuring the fermion spectral function through momentum-resolved microwave spectroscopy and without spurious effects from final-state interactions. The temperature dependence of the pairing gap, inverse pair lifetime and single-particle scattering rate are quantitatively determined by analysing the spectra. We find a large pseudogap above the superfluid transition temperature. The inverse pair lifetime exhibits a thermally activated exponential behaviour, uncovering the microscopic virtual pair breaking and recombination mechanism. The obtained large, temperature-independent single-particle scattering rate is comparable with that set by the Planckian limit. Our findings quantitatively characterize the pseudogap in strongly interacting Fermi gases and they lend support for the role of preformed pairing as a precursor to superfluidity.
DOI: 10.1038/s41586-023-06964-y
Source: https://www.nature.com/articles/s41586-023-06964-y
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html