Observation and quantification of pseudogap in unitary Fermi gases
Abstract
The nature of pseudogap lies at the heart of strongly-interacting superconductivity and superfluidity. With known pairing interactions, unitary Fermi gases provide an ideal testbed to verify whether a pseudogap can arise from many-body pairing. Here we report the observation of the long-sought pair-fluctuation-driven pseudogap in homogeneous unitary Fermi gases of lithium-6 atoms, by precisely measuring the spectral function through momentum-resolved microwave spectroscopy without the serious effects of final-state effect. We find a large pseudogap above the superfluid transition. The inverse pair lifetime exhibits a thermally-activated exponential behavior, uncovering the microscopic virtual pair breaking and recombination mechanism. The obtained large, T-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, highlighting the role of preformed pairing as a precursor to superfluidity.
Keywords
Cite
@article{arxiv.2310.14024,
title = {Observation and quantification of pseudogap in unitary Fermi gases},
author = {Xi Li and Shuai Wang and Xiang Luo and Yu-Yang Zhou and Ke Xie and Hong-Chi Shen and Yu-Zhao Nie and Qijin Chen and Hui Hu and Yu-Ao Chen and Xing-Can Yao and Jian-Wei Pan},
journal= {arXiv preprint arXiv:2310.14024},
year = {2023}
}