我们从实验和理论上研究了冷原子从磁光阱（MOT）到有限深度阱的连续积累，包括由射频（RF）场修饰的磁四极阱。MOT中的铬原子（52同位素）被MOT激光器连续地光学泵浦到亚稳态暗态。在存在射频场的情况下，被磁俘获的亚稳态原子的温度可以低至25微K，密度为10 ^17原子·m-3，导致相空间密度增加，但仍被非弹性碰撞限制在7.10^-6。为了研究截断磁阱中的热化问题，我们测量了射频截断磁阱中原子的自由蒸发速率，并推导出原子处于5D 4亚稳态时的平均弹性截面为7.0 × 10^-16 m 2.
英文摘要：
We experimentally and theoretically study the continuous accumulation of cold atoms from a magneto-optical trap (MOT) into a finite depth trap, consisting in a magnetic quadrupole trap dressed by a radiofrequency (RF) field. Chromium atoms (52 isotope) in a MOT are continuously optically pumped by the MOT lasers to metastable dark states. In presence of a RF field, the temperature of the metastable atoms that remain magnetically trapped can be as low as 25 microK, with a density of 10^17 atoms.m-3, resulting in an increase of the phase-space density, still limited to 7.10^-6 by inelastic collisions. To investigate the thermalization issues in the truncated trap, we measure the free evaporation rate in the RF-truncated magnetic trap, and deduce the average elastic cross section for atoms in the 5D4 metastable states, equal to 7.0 10^-16m2.
Thermalization measurements on an ultracold mixture of metastable $^4$He and $^{87}$Rb atoms in a quadrupole magnetic trap
最近，我们报道了（Knoop等人[arXiv：1404.4826]）通过在四极磁阱中对超冷混合物进行热化测量，实验测定亚稳态三重态$^4$ He+ $^{87}$ Rb散射长度。在这里，我们提出了我们的实验装置，并详细说明这些热化测量。特别地，我们给出了四极磁阱种间热化率的理论描述。e.在Majorana加热的存在下，和一个通用的程序来提取散射长度从弹性截面在有限温度下的$C_6$系数的知识的基础上单独。此外，从我们的热化数据中，我们得到了一个上限的总种间两体损失率系数$1.5\times 10^{-12}$ cm $^3$ s $^{-1}$。
