Mihaila Bogdan, Gaudio Sergio, Blagoev Krastan B, Balatsky Alexander V, Littlewood Peter B, Smith Darryl L
Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Phys Rev Lett. 2005 Aug 26;95(9):090402. doi: 10.1103/PhysRevLett.95.090402. Epub 2005 Aug 25.
We propose a new method of detecting the onset of superfluidity in a two-component ultracold fermionic gas of atoms governed by an attractive short-range interaction. By studying the two-body correlation functions we find that a measurement of the momentum distribution of the density and spin-response functions allows one to access separately the normal and anomalous densities. The change in sign at low momentum transfer of the normal-ordered part of the density response function signals the transition between a BEC and a BCS regime, characterized by small and large pairs, respectively. This change in sign of the density response function represents an unambiguous signature of the BEC-to-BCS crossover. Spin rotational symmetry breaking due to the magnetic field, if observed, can be used to validate the one-channel model.
我们提出了一种新方法，用于检测由吸引性短程相互作用支配的双组分超冷费米原子气体中超流性的起始。通过研究两体关联函数，我们发现对密度和自旋响应函数的动量分布进行测量能够分别获取正常密度和反常密度。密度响应函数的正常排序部分在低动量转移时符号的变化标志着玻色-爱因斯坦凝聚（BEC）和玻色-库珀对超流（BCS） regime之间的转变，分别以小对和大对为特征。密度响应函数符号的这种变化代表了BEC到BCS交叉的明确标志。如果观察到由于磁场导致的自旋旋转对称性破缺，则可用于验证单通道模型。
