Abstract

The “mixing” of magnetic sublevels of the ground and excited levels of an atomic transition with magnetic sublevels of a nearby transition (in the hyperfine structure of atoms of alkali metals) is responsible for a strong modification of its probability. A dramatic manifestation of this mixing effect is a huge increase in the probability of the atomic transition in magnetic fields that is forbidden by selection rules in zero magnetic field B = 0; the latter is called a magnetically induced (MI) transition. Two MI transitions with different dependences on B have been studied. Another dramatic manifestation of the mixing effect is that there are atomic transitions whose frequency is practically fixed in a wide range of magnetic fields, i.e., the slope S [MHz/G] of the frequency shifts as a function of B is practically zero, with the transition probability being significant. We call these transitions “unmoved” transitions (UTs). We have studied the UTs of ⁸⁷Rb atoms, the D₂ line, |1, +1〉 → |1', +1'〉 and Cs atoms, the D₂ line, |3, –3〉 → |5', –4'〉, where the quantum numbers F and m_F of the excited and ground levels are marked with and without primes, respectively. We show that in the range B = 180–705 G for ⁸⁷Rb, the D₂ line, |S| ≤ 0.03 MHz/G; for comparison, S ≈ 3.6 MHz/G for ⁸⁷Rb in the same B range for the MI transition |1, +1〉 → |3', +2'〉 is greater by a factor of 120. A second laser was used to control the UT amplitude. Our theoretical model describes well the experiment.

中文翻译：

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外部磁场中碱金属的“不变”原子跃迁

摘要

地磁子能级和原子跃迁的激发能级与附近跃迁的磁子能级（在碱金属原子的超精细结构中）的“混合”是其概率的强烈改变的原因。这种混合效应的一个显着表现是，磁场中原子跃迁的可能性大大增加，这是由零磁场B = 0中的选择规则所禁止的。后者称为磁感应（MI）跃迁。已经研究了两个对B有不同依赖性的MI跃迁。混合效应的另一个戏剧性表现是存在原子跃迁，其频率实际上在宽范围的磁场（即斜率S）中固定不变频移的[MHz / G]作为B的函数实际上为零，跃迁几率很大。我们将这些过渡称为“不变”过渡（UT）。我们研究了^87个Rb原子的UT ，D ₂线| 1，+1〉→| 1'，+1'〉和Cs原子，D ₂线| 3，–3〉→| 5'， –4'〉，其中激发能级和基能级的量子数F和m _F分别标有和没有素数。我们表明，在该范围内乙= 180-705 G代表⁸⁷ RB，则d ₂线，| S | ≤0.03 MHz / G; 为了比较，S在MI过渡| 1，+1>→| 3'，+2'>的相同B范围内，对于⁸⁷ Rb≈3.6 MHz / G增大了120倍。使用第二个激光来控制UT幅度。我们的理论模型很好地描述了实验。