Department of Applied Physics, Stanford University, Stanford, California 94305, USA and E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
Department of Physics, Stanford University, Stanford, California 94305, USA and E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2015 Jan 16;114(2):023201. doi: 10.1103/PhysRevLett.114.023201. Epub 2015 Jan 14.
We observe the suppression of inelastic dipolar scattering in ultracold Fermi gases of the highly magnetic atom dysprosium: the more energy that is released, the less frequently these exothermic reactions take place, and only quantum spin statistics can explain this counterintuitive effect. Inelastic dipolar scattering in nonzero magnetic fields leads to heating or to loss of the trapped population, both detrimental to experiments intended to study quantum many-body physics with strongly dipolar gases. Fermi statistics, however, is predicted to lead to a kinematic suppression of these harmful reactions. Indeed, we observe a 120-fold suppression of dipolar relaxation in fermionic versus bosonic Dy, as expected from theory describing universal inelastic dipolar scattering, though never before experimentally confirmed. Similarly, low inelastic cross sections are observed in spin mixtures, also with striking correspondence to predictions. The suppression of relaxation opens the possibility of employing fermionic dipolar species in studies of quantum many-body physics involving, e.g., synthetic gauge fields and pairing.
我们观察到在强磁场原子镝的超冷费米气体中，非弹性偶极散射被抑制：释放的能量越多，这些放热反应发生的频率就越低，只有量子自旋统计才能解释这种违反直觉的效应。非零磁场中的非弹性偶极散射会导致加热或囚禁粒子的损失，这两种情况都不利于用强偶极气体研究量子多体物理的实验。然而，费米统计预计会对这些有害反应产生运动学抑制。事实上，正如描述普遍非弹性偶极散射的理论所预测的那样，我们观察到在费米子与玻色子 Dy 之间，偶极弛豫的抑制作用高达 120 倍，尽管此前从未在实验中得到证实。同样，在自旋混合物中也观察到低的非弹性截面，这与预测结果具有惊人的一致性。弛豫的抑制为使用费米子偶极体研究涉及例如合成规范场和配对的量子多体物理提供了可能性。
