Reducing the Instability of an Optical Lattice Clock Using Multiple Atomic Ensembles
Reducing the Instability of an Optical Lattice Clock Using Multiple Atomic Ensembles
复制标题
DOI：
10.1103/physrevx.14.011006
复制
发表时间：
2023-05
影响因子：
12.5
通讯作者：
Xin Zheng;J. Dolde;S. Kolkowitz
中科院分区：
文献类型：
--
作者：
Xin Zheng;J. Dolde;S. Kolkowitz
光学原子钟的稳定性是几乎所有时钟应用的关键品质因数。为此，许多光学原子钟的研究都集中在通过增加原子数、延长相干询问时间和引入纠缠以超越标准量子极限来减少时钟不稳定性。在这项工作中，我们实验证明了一种替代方法，以减少时钟的不稳定性使用的相位估计方法的基础上单独控制的原子系综在锶（Sr）光晶格时钟。我们首先展示了两个空间分辨原子系综的联合拉姆齐询问，它们彼此异相，我们称之为“正交拉姆齐光谱“，导致绝对时钟不稳定性降低1.36（5）倍，如用交错自比较测量的。然后，我们利用${}^{87}$Sr的丰富的超精细结构，仅用全局激光寻址来实现对多个系综的独立相干控制。最后，我们利用这种独立的控制4原子系综实现一种形式的相位估计，实现了一个因素大于3增强相干询问时间和2.08（6）的因素减少不稳定性，否则相同的单系综时钟具有相同的本地振荡器和相同数量的原子。我们预计，多合奏协议类似于这里所展示的将导致在任何光晶格时钟的不稳定性减少与本地振荡器的询问时间限制。
The stability of an optical atomic clock is a critical figure of merit for almost all clock applications. To this end, much optical atomic clock research has focused on reducing clock instability by increasing the atom number, lengthening the coherent interrogation times, and introducing entanglement to push beyond the standard quantum limit. In this work, we experimentally demonstrate an alternative approach to reducing clock instability using a phase estimation approach based on individually controlled atomic ensembles in a strontium (Sr) optical lattice clock. We first demonstrate joint Ramsey interrogation of two spatially-resolved atom ensembles that are out of phase with respect to each other, which we call"quadrature Ramsey spectroscopy,"resulting in a factor of 1.36(5) reduction in absolute clock instability as measured with interleaved self-comparisons. We then leverage the rich hyperfine structure of ${}^{87}$Sr to realize independent coherent control over multiple ensembles with only global laser addressing. Finally, we utilize this independent control over 4 atom ensembles to implement a form of phase estimation, achieving a factor of greater than 3 enhancement in coherent interrogation time and a factor of 2.08(6) reduction in instability over an otherwise identical single ensemble clock with the same local oscillator and the same number of atoms. We expect that multi-ensemble protocols similar to those demonstrated here will result in reduction in the instability of any optical lattice clock with an interrogation time limited by the local oscillator.