超流费米气体的量子蒙特卡罗研究
Quantum Monte Carlo Studies of Superfluid Fermi Gases
摘要：
本文报道了具有吸引短程两体相互作用的稀费米气体基态的量子Monte Carlo计算结果。的相互作用的强度是不同的，以研究不同的配对制度，其特征在于由产品的s-波散射长度和费米波矢量，$ak_F$。我们报告的基态能量，配对间隙$Δ$和准粒子谱的结果。在弱耦合区域$1/ak_F < -1$，我们得到BCS超流体，能隙$Δ$远小于费米气体能量$E_{FG}$ .当$ a > 0$时，相互作用足够强以形成具有能量$E_{mol}$的结合分子。对于$1/ak_F \gtrsim 0.5$，我们发现在超流气体中形成了弱相互作用的复合玻色子，其$Δ$和气体的每粒子能量接近$|E_{mol}|/2$。在这个区域中，我们似乎有分子的玻色-爱因斯坦凝聚（BEC）。讨论了BCS到BEC过渡区$-0.5 < 1/ak_F < 0.5$的能量和带隙的变化。
英文摘要：
We report results of quantum Monte Carlo calculations of the ground state of dilute Fermi gases with attractive short range two-body interactions. The strength of the interaction is varied to study different pairing regimes which are characterized by the product of the s-wave scattering length and the Fermi wave vector, $ak_F$. We report results for the ground state energy, the pairing gap $Δ$ and the quasiparticle spectrum. In the weak coupling regime, $1/ak_F < -1$, we obtain BCS superfluid and the energy gap $Δ$ is much smaller than the Fermi gas energy $E_{FG}$. When $ a > 0$, the interaction is strong enough to form bound molecules with energy $E_{mol}$. For $1/ak_F \gtrsim 0.5$ we find that weakly interacting composite bosons are formed in the superfluid gas with $Δ$ and gas energy per particle approaching $|E_{mol}|/2$. In this region we seem to have Bose-Einstein condensation (BEC) of molecules. The behavior of the energy and the gap in the BCS to BEC transition region, $-0.5 < 1/ak_F < 0.5$ is discussed.
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