FYI (First appeared on arXiv in May, 2017): https://www.sciencedaily.com/releases/2017/12/171222092504.htm http://science.sciencemag.org/content/early/2017/12/20/science.aan5950 https://arxiv.org/abs/1705.10577
"The nature of the normal phase of strongly correlated fermionic systems is an outstanding question in quantum many-body physics. We use spatially resolved radio-frequency spectroscopy to measure pairing energy of fermions across a wide range of temperatures and interaction strengths in a two-dimensional gas of ultracold fermionic atoms. We observe many-body pairing at temperatures far above the critical temperature for superfluidity. In the strongly interacting regime, the pairing energy in the normal phase significantly exceeds the intrinsic two-body binding energy of the system and shows a clear dependence on local density. This implies that pairing in this regime is driven by many-body correlations, rather than two-body physics. Our findings show that pairing correlations in strongly interacting two-dimensional fermionic systems are remarkably robust against thermal fluctuations." Some excerpts from/following above links: "We perform our experiments with a two-component mixture of 6Li atoms with approximately 3 × 104 particles per spin state that are loaded into a single layer of an anisotropic harmonic optical trap." "Using a technique known as radio-frequency spectroscopy, the researchers measured the response of the atoms to a radio-wave pulse. From this response, they could tell exactly whether or not the particles were paired and in what way." "Beyond this previously explored regime, our measurements reveal that many-body effects enhance the pairing energy far above the critical temperature, with the maximum enhancement occurring at ln(kFa2D) ≈ 1, where a reliable mean-field description is not available."
