Near-threshold scaling of resonant inelastic collisions at ultralow temperatures
Near-threshold scaling of resonant inelastic collisions at ultralow temperatures
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DOI：
10.1103/physreva.105.l011302
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发表时间：
2021-05
影响因子：
2.9
通讯作者：
R. Hermsmeier;A. Devolder;P. Brumer;T. Tscherbul
中科院分区：
文献类型：
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作者：
R. Hermsmeier;A. Devolder;P. Brumer;T. Tscherbul
我们表明，在很宽的范围内，伴随着激发交换的共振非弹性过程的截面（如自旋交换，Förster共振或角动量交换）表现出非常规的近阈值标度E <$m12，其中E是碰撞能量，<$m12 = m1 + m2 − m1 − m2，mi和mi是碰撞物质的初始和最终角动量投影（i = 1，2）。特别是，非弹性截面为12 = 0过渡显示一个非常规的E0标度类似的弹性截面，和他们的速率消失为T 12 + 12。对于由偶次分波主导的碰撞（例如在相同内部状态下的完全相同玻色子），如果ε m 12是奇数，则标度被修改为σinel ε E ε m 12 +1。我们提出了精确的量子散射计算，说明这些修改后的阈值法律共振自旋交换超冷Rb + Rb和O2 + O2碰撞。我们的研究结果表明，碰撞截面的阈值缩放仅由基本过程的能量（共振与放热），而不是由碰撞粒子的内部状态是否在碰撞中发生变化。
We show that the cross sections for a broad range of resonant inelastic processes accompanied by excitation exchange (such as spin-exchange, Förster resonant, or angular momentum exchange) exhibit an unconventional near-threshold scaling E∆m12 , where E is the collision energy, ∆m12 = m1 + m2 − m1 − m2, and mi and mi are the initial and final angular momentum projections of the colliding species (i = 1, 2). In particular, the inelastic cross sections for ∆m12 = 0 transitions display an unconventional E0 scaling similar to that of elastic cross sections, and their rates vanish as T∆m12+1/2. For collisions dominated by even partial waves (such as those of identical bosons in the same internal state) the scaling is modified to σinel ∝ E∆m12+1 if ∆m12 is odd. We present accurate quantum scattering calculations that illustrate these modified threshold laws for resonant spin exchange in ultracold Rb + Rb and O2 + O2 collisions. Our results illustrate that the threshold scaling of collision cross sections is determined only by the energetics of the underlying process (resonant vs. exothermic) rather than by whether the internal states of colliding particles is changed in the collision.