Huntemann N, Sanner C, Lipphardt B, Tamm Chr, Peik E
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
Phys Rev Lett. 2016 Feb 12;116(6):063001. doi: 10.1103/PhysRevLett.116.063001. Epub 2016 Feb 8.
We experimentally investigate an optical frequency standard based on the (2)S1/2(F=0)→(2)F7/2(F=3) electric octupole (E3) transition of a single trapped (171)Yb+ ion. For the spectroscopy of this strongly forbidden transition, we utilize a Ramsey-type excitation scheme that provides immunity to probe-induced frequency shifts. The cancellation of these shifts is controlled by interleaved single-pulse Rabi spectroscopy, which reduces the related relative frequency uncertainty to 1.1×10(-18). To determine the frequency shift due to thermal radiation emitted by the ion's environment, we measure the static scalar differential polarizability of the E3 transition as 0.888(16)×10(-40) J m(2)/V(2) and a dynamic correction η(300 K)=-0.0015(7). This reduces the uncertainty due to thermal radiation to 1.8×10(-18). The residual motion of the ion yields the largest contribution (2.1×10(-18)) to the total systematic relative uncertainty of the clock of 3.2×10(-18).
我们通过实验研究了一种基于单个囚禁的（171）Yb⁺离子的（2）S1/2（F = 0）→（2）F7/2（F = 3）电八极（E3）跃迁的光频标准。对于这种强禁戒跃迁的光谱学研究，我们采用了一种拉姆齐型激发方案，该方案可消除探测引起的频移。这些频移的消除由交错单脉冲拉比光谱控制，这将相关的相对频率不确定度降低到1.1×10⁻¹⁸。为了确定由离子环境发出的热辐射引起的频移，我们测量了E3跃迁的静态标量微分极化率为0.888(16)×10⁻⁴⁰ J m²/V²，以及动态修正η(300 K)= -0.0015(7)。这将热辐射引起的不确定度降低到1.8×10⁻¹⁸。离子的剩余运动对时钟总系统相对不确定度3.2×10⁻¹⁸的贡献最大（2.1×10⁻¹⁸）。
