Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas
Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas
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DOI：
10.1103/physreva.82.043630
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发表时间：
2010-07
影响因子：
2.9
通讯作者：
R. Watanabe;S. Tsuchiya;Y. Ohashi
中科院分区：
文献类型：
--
作者：
R. Watanabe;S. Tsuchiya;Y. Ohashi
我们研究了超流体费米气体中BCS-BEC交叉态的单粒子激发和强耦合效应。在T矩阵理论中，包括超流体序参量的相位和振幅波动，我们计算了在超流体转变温度T{sub c}以下的整个BCS-BEC交叉区域的超流体态密度（DOS）以及单粒子谱权。我们阐明了当一个人通过T{sub c}时，正常状态下的赝隙是如何演变成超流体隙的。在弱耦合BCS区，DOS中的赝隙不断演化为超流隙，在T{sub c}以下赝隙消失后，DOS中出现了交叉区超流隙。在关于温度和相互作用强度的相图中，我们确定了强配对波动支配系统单粒子性质的区域。我们的研究结果对研究超流体费米气体的BCS-BEC交叉态中的强耦合现象具有重要意义。
We investigate single-particle excitations and strong-coupling effects in the BCS-BEC crossover regime of a superfluid Fermi gas. Including phase and amplitude fluctuations of the superfluid order parameter within a T-matrix theory, we calculate the superfluid density of states (DOS), as well as single-particle spectral weight, over the entire BCS-BEC crossover region below the superfluid transition temperature T{sub c}. We clarify how the pseudogap in the normal state evolves into the superfluid gap, as one passes through T{sub c}. While the pseudogap in DOS continuously evolves into the superfluid gap in the weak-coupling BCS regime, the superfluid gap in the crossover region is shown to appear in DOS after the pseudogap disappears below T{sub c}. In the phase diagram with respect to the temperature and interaction strength, we determine the region where strong pairing fluctuations dominate over single-particle properties of the system. Our results would be useful for the study of strong-coupling phenomena in the BCS-BEC crossover regime of a superfluid Fermi gas.