Suppression of Collisional Shifts in a Strongly Interacting Lattice Clock
Suppression of Collisional Shifts in a Strongly Interacting Lattice Clock
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DOI：
10.1126/science.1196442
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发表时间：
2010-07
期刊：
影响因子：
56.9
通讯作者：
M. Swallows;M. Bishof;Yige Lin;S. Blatt;Michael J. Martin;A. Rey;Jun Ye
中科院分区：
文献类型：
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作者：
M. Swallows;M. Bishof;Yige Lin;S. Blatt;Michael J. Martin;A. Rey;Jun Ye
保持时间光学晶格钟由放置在光学晶格中的原子组成，该光学晶格由相对的激光束形成，并且由于其工作频率更高以及可供询问的原子数量比传统微波原子钟更精确。然而，原子之间的相互作用可能会导致时钟跃迁频率的变化，通常与原子密度成正比。燕子等人。 （第 1043 页，2 月 3 日在线发布）展示了相互作用的相反且意想不到的效果：对于足够强的相互作用系统，频移被抑制。事实上，在基于锶的费米子晶格时钟中，偏移及其相关的扩展减少了一个数量级。增加原子相互作用提高了由光学晶格中捕获的原子形成的时钟的准确性和精确度。当同时询问许多原子时，具有极其稳定频率的光学晶格时钟是可能的，但这种精度可能是以原子相互作用导致的系统不准确为代价的。即使在使用费米子原子的时钟中，如果它们受到不均匀的光学激发，也会发生与密度相关的频移。然而，足够强的相互作用可以抑制包含多个原子的晶格位点的碰撞位移。我们通过将碰撞频移及其不确定性降低到 10−17 的水平，用锶晶格时钟证明了这种方法的有效性。这一结果消除了多粒子系统中精度和准确度之间的折衷；随着粒子数量的增加，两者都会继续改善。
Keeping Time Optical lattice clocks are comprised of atoms placed in an optical lattice formed by opposing laser beams and can be more precise than traditional microwave atomic clocks because of the higher frequency at which they operate, and the number of atoms available for interrogation. However, interactions between the atoms may lead to shifts in the frequency of the clock transition, usually proportional to the atomic density. Swallows et al. (p. 1043, published online 3 February) demonstrate an opposite and unexpected effect of interactions: For sufficiently strongly interacting systems, the frequency shift is suppressed. Indeed, in a strontium-based fermionic lattice clock, the shift and its associated spread were reduced by an order of magnitude. Increasing atomic interactions improved the accuracy and precision of a clock formed from atoms trapped in an optical lattice. Optical lattice clocks with extremely stable frequency are possible when many atoms are interrogated simultaneously, but this precision may come at the cost of systematic inaccuracy resulting from atomic interactions. Density-dependent frequency shifts can occur even in a clock that uses fermionic atoms if they are subject to inhomogeneous optical excitation. However, sufficiently strong interactions can suppress collisional shifts in lattice sites containing more than one atom. We demonstrated the effectiveness of this approach with a strontium lattice clock by reducing both the collisional frequency shift and its uncertainty to the level of 10−17. This result eliminates the compromise between precision and accuracy in a many-particle system; both will continue to improve as the number of particles increases.