Observation of a pairing pseudogap in a two-dimensional Fermi gas

Abstract

Pairing of fermions is ubiquitous in nature and it is responsible for a large variety of fascinating phenomena like superconductivity, superfluidity of ${}^3$He, the anomalous rotation of neutron stars, and the BEC-BCS crossover in strongly interacting Fermi gases. When confined to two dimensions, interacting many-body systems bear even more subtle effects, many of which lack understanding at a fundamental level. Most striking is the, yet unexplained, effect of high-temperature superconductivity in cuprates, which is intimately related to the two-dimensional geometry of the crystal structure. In particular, the questions how many-body pairing is established at high temperature and whether it precedes superconductivity are crucial to be answered. Here, we report on the observation of pairing in a harmonically trapped two-dimensional atomic Fermi gas in the regime of strong coupling. We perform momentum-resolved photoemission spectroscopy, analogous to ARPES in the solid state, to measure the spectral function of the gas and we detect a many-body pairing gap above the superfluid transition temperature. Our observations mark a significant step in the emulation of layered two-dimensional strongly correlated superconductors using ultracold atomic gases.

References in corpus (11)

• Many-Body Physics with Ultracold Gases
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Attractive and repulsive Fermi polarons in two dimensions
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Observation of a two-dimensional Fermi gas of atoms
• Tomographic RF Spectroscopy of a Trapped Fermi Gas at Unitarity
• Crossover from 2D to 3D in a weakly interacting Fermi gas
• Measuring the one-particle excitations of ultracold fermionic atoms by stimulated Raman spectroscopy
• Pseudo-gap pairing in ultracold Fermi atoms
• Pairing-gap, pseudo-gap, and no-gap phases in the radio-frequency spectra of a trapped unitary 6Li gas

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