Pair correlations in the two-dimensional Fermi gas.
We consider the two-dimensional Fermi gas at finite temperature with attractive short-range interactions. Using the virial expansion, which provides a controlled approach at high temperatures, we determine the spectral function and contact for the normal state. Our calculated spectra are in qualitative agreement with recent photoemission measurements [M. Feld et al., Nature (London) 480, 75 (2011).], thus suggesting that the observed pairing gap is a feature of the high-temperature gas rather than being evidence of a pseudogap regime just above the superfluid transition temperature. We further argue that the strong pair correlations result from the fact that the crossover to bosonic dimers occurs at weaker interactions than previously assumed.
T.C.M. Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
Vudtiwat
V
Ngampruetikorn
T.C.M. Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom and Aarhus Institute of Advanced Studies, Aarhus University, DK-8000 Aarhus C, Denmark.
Jesper
J
Levinsen
London Centre for Nanotechnology, Gordon Street, London WC1H 0AH, United Kingdom.
Meera M
MM
Parish