Comparative study of strong-coupling theories of a trapped Fermi gas at unitarity

We present a systematic comparison of the most recent thermodynamic measurements of a trapped Fermi gas at unitarity with predictions from strong-coupling theories and quantum Monte Carlo (MC) simulations. The accuracy of the experimental data, of the order of a few percent, allows a precise test of different many-body approaches. We find that a Nozières and Schmitt-Rink treatment of fluctuations is in excellent agreement with the experimental data and available MC calculations at unitarity.

Figure 1

(Color online) Chemical potential of a uniform Fermi gas at unitarity as a function of reduced temperature $T∕T_F$, where $T_F={ϵ}_F∕k_B$. The lines plotted are the results of NSR (solid lines), $\left(G{G}_0\right)G_0$ (dashed line), $\left(GG\right)G$ (dotted line), and pesudogap model (dotted-dashed line). These predictions are compared with lattice QMC simulations (symbols).

Figure 2

(Color online) Temperature dependence of the energy (upper panel) and of the entropy (lower panel) of a uniform Fermi gas at unitarity, obtained from different $T$-matrix approximations and QMC simulations as indicated.

Figure 3

(Color online) Theoretically predicted universal thermodynamics in comparison with experimental data [18].