Schedule Oct 15, 2010
Thermodynamics in a Unitary Fermi Gas
Kaijun Jiang (Chinese Academy of Sci.)

Kaijun Jiang1,2, Sylvain Nascimbene2, Nir Navon2, Frederic Chevy2, Christophe Salomon2

1Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
2Laboratoire Kastler Brossel, Ecole Normale Superieure, Paris 75005, France

       Strong interaction in ultracold Fermi gas is a controllable and reachable quantum simulator to study many-body problems [1] which generally happen from high-energy particle physics to condensed matter and astrophysics. Microscopic strong interaction makes it really difficult to analytically solve this process, where Monte Carlo simulation [2] can be a valid method to predict thermodynamics in this regime. So model-independent measurement becomes a long-term regarded focus for experiments. Previously, trap averaged thermodynamics was reached in this strong interaction by JILA [3] and Rice University [4]. In this poster, we will briefly introduce a new experimental technique to measure thermodynamics details in unitary regime, using local density approximation and in-situ atomic density imaging. Our method is precise and efficient enough to compare previously many-body theoretical predictions. For the balanced Fermi gas above the threshold temperature, it is a surprise that Fermi liquid theory agrees well with the experimental results without measurable pairing gap. The phase transition temperature and density jumping in this point have a good agreement with previously predictions and measurements. For the imbalanced Fermi gas in zero temperature, spatial phase separation takes place for different spin polarization. Ideal gas, superfluid and Fermi polaron models can describe these three phases as well respectively. The details of the poster can be found in paper [5]

[1], S.Giorgini, L. P.Pitaevskii, and S.Stringari, Rev. Mod. Phys., 80, 1216, 2008
[2], E.Burovski, N. Prokofev, B. Svistunov, and M. Troyer, Phys. Rev. Lett., 96, 160402, 2006; A.Bulgac, J. Drut, and P. Magierski, Phys. Rev. Lett., 96, 090404, 2006.
[3], J. Stewart, J. Gaebler, C. Regal, and D. Jin, Phys. Rev. Lett., 97, 220406, 2006.
[4], L. Luo, B. Clancy, J. Joseph, J. Kinast, and J. Thomas, Phys. Rev. Lett., 98, 080402, 2007.
[5], S. Nascimbene, N. Navon, K. J. Jiang, F. Chevy and C. Salomon, Nature, 463, 1057, 2010.

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