Title: High temperature pairing in a strongly interacting two-dimensional Fermi gas,
Abstract: We observe many-body pairing in a two-dimensional gas of ultracold fermionic
atoms at temperatures far above the critical temperature for superfluidity. For
this, we use spatially resolved radio-frequency spectroscopy to measure pairing
energies spanning a wide range of temperatures and interaction strengths. In
the strongly interacting regime where the scattering length between fermions is
on the same order as the inter-particle spacing, 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. We find this effect to persist at temperatures close to the Fermi
temperature which demonstrates that pairing correlations in strongly
interacting two-dimensional fermionic systems are remarkably robust against
thermal fluctuations.