Max-Planck-Institut für Quantenoptik, Garching, Germany.
Phys Rev Lett. 2011 Nov 11;107(20):203001. doi: 10.1103/PhysRevLett.107.203001.
We have measured the 1S-2S transition frequency in atomic hydrogen via two-photon spectroscopy on a 5.8 K atomic beam. We obtain f(1S-2S) = 2,466,061,413,187,035 (10) Hz for the hyperfine centroid, in agreement with, but 3.3 times better than the previous result [M. Fischer et al., Phys. Rev. Lett. 92, 230802 (2004)]. The improvement to a fractional frequency uncertainty of 4.2 × 10(-15) arises mainly from an improved stability of the spectroscopy laser, and a better determination of the main systematic uncertainties, namely, the second order Doppler and ac and dc Stark shifts. The probe laser frequency was phase coherently linked to the mobile cesium fountain clock FOM via a frequency comb.
我们通过 5.8 K 原子束的双光子光谱测量了氢原子的 1S-2S 跃迁频率。我们得到的超精细质心的 f(1S-2S) = 2,466,061,413,187,035 (10) Hz，与之前的结果[M. Fischer 等人，物理评论快报 92, 230802 (2004)]一致，但精度提高了 3.3 倍。分数频率不确定度提高到 4.2 × 10(-15)主要是由于光谱激光稳定性的提高，以及对主要系统不确定性的更好确定，即二阶多普勒和 ac 和 dc 斯塔克频移。探测激光频率通过频梳与移动的铯喷泉钟 FOM 进行相位相干连接。
