Ultrastable optical clock with two cold-atom ensembles
Ultrastable optical clock with two cold-atom ensembles
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DOI：
10.1038/nphoton.2016.231
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发表时间：
2016-07
期刊：
影响因子：
35
通讯作者：
M. Schioppo;M. Schioppo;M. Schioppo;Roger Brown;W. McGrew;W. McGrew;N. Hinkley;N. Hinkley;
中科院分区：
文献类型：
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作者：
M. Schioppo;M. Schioppo;M. Schioppo;Roger Brown;W. McGrew;W. McGrew;N. Hinkley;N. Hinkley;
基于光学跃迁的原子钟是最稳定的，因此也是最精确的计时器。这些时钟通过交替原子询问的间隔与量子态制备和读出所需的“死”时间来运行。这种对原子系统的非连续询问会导致迪克效应，即来自询问原子跃迁的激光的频率噪声的混叠。尽管最近通过提高激光相干性在光学时钟稳定性方面取得了进展，但Dick效应一直限制着光学时钟的性能。在这里，我们实现了一个强大的解决方案，以克服这一限制：零死区时间的光学时钟，是基于两个冷原子合奏交错询问。该时钟表现出非常小的Dick噪声，从而实现了前所未有的分数频率不稳定性，估计为平均时间τ（以秒为单位）。我们还考虑了替代的双原子系综方案来扩展激光相干性并降低时钟稳定性的标准量子极限，实现了Q> 4× 1015的光谱线品质因子。
Atomic clocks based on optical transitions are the most stable, and therefore precise, timekeepers available. These clocks operate by alternating intervals of atomic interrogation with the ‘dead’time required for quantum state preparation and readout. This non-continuous interrogation of the atom system results in the Dick effect, an aliasing of frequency noise from the laser interrogating the atomic transition,. Despite recent advances in optical clock stability that have been achieved by improving laser coherence, the Dick effect has continually limited the performance of optical clocks. Here we implement a robust solution to overcome this limitation: a zero-dead-time optical clock that is based on the interleaved interrogation of two cold-atom ensembles. This clock exhibits vanishingly small Dick noise, thereby achieving an unprecedented fractional frequency instability assessed to be for an averaging time τ in seconds. We also consider alternate dual-atom-ensemble schemes to extend laser coherence and reduce the standard quantum limit of clock stability, achieving a spectroscopy line quality factor of Q> 4× 1015.