Regal C A, Greiner M, Jin D S
JILA, National Institute of Standards and Technology and University of Colorado, Boulder, CO 80309-0440, USA.
Phys Rev Lett. 2004 Jan 30;92(4):040403. doi: 10.1103/PhysRevLett.92.040403. Epub 2004 Jan 28.
We have observed condensation of fermionic atom pairs in the BCS-BEC crossover regime. A trapped gas of fermionic 40K atoms is evaporatively cooled to quantum degeneracy and then a magnetic-field Feshbach resonance is used to control the atom-atom interactions. The location of this resonance is precisely determined from low-density measurements of molecule dissociation. In order to search for condensation on either side of the resonance, we introduce a technique that pairwise projects fermionic atoms onto molecules; this enables us to measure the momentum distribution of fermionic atom pairs. The transition to condensation of fermionic atom pairs is mapped out as a function of the initial atom gas temperature T compared to the Fermi temperature T(F) for magnetic-field detunings on both the BCS and BEC sides of the resonance.
我们已经在BCS-BEC交叉区域观测到了费米子原子对的凝聚。捕获的费米子40K原子气体通过蒸发冷却至量子简并，然后利用磁场费什巴赫共振来控制原子间相互作用。该共振的位置通过分子解离的低密度测量精确确定。为了在共振两侧寻找凝聚现象，我们引入了一种将费米子原子成对投影到分子上的技术；这使我们能够测量费米子原子对的动量分布。对于共振的BCS和BEC两侧的磁场失谐，将费米子原子对凝聚的转变描绘为初始原子气体温度T与费米温度T(F)之比的函数。
