We propose 10 highly-charged ions as candidates for the development of next generation atomic clocks, quantum information, and search for $α$-variation. They have long-lived metastable states with transition frequencies to the ground state between 170-3000 nm, relatively simple electronic structure, stable isotopes and high sensitivity to $α$-variation (e.g., Sm$^{14+}$, Pr$^{10+}$, Sm$^{13+}$, Nd$^{10+}$). We predict their properties crucial for the experimental exploration and highlight particularly attractive systems for these applications.
Proposal for a multi-ion optical clock with hundreds of ions
P.N. Lebedev Physical Institute of the Russian Academy of Sciences（俄罗斯科学院列别杰夫物理研究所）；Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), School of Physics, Renmin University of China（中国人民大学物理学院量子态构建与操控教育部重点实验室）；Russian Quantum Center, Skolkovo（斯科尔科沃俄罗斯量子中心）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）
We identify laser-accessible transitions in group 16-like highly charged ions as candidates for high-accuracy optical clocks, including S-, Se-, and Te-like systems. For this class of ions, the ground $^{3}P_{J}$ fine structure manifold exhibits irregular (nonmonotonic in $J$) energy ordering for large enough ionization degree. We consider the $|^3P_2\rangle \longleftrightarrow |^3P_0\rangle$ (ground to first-excited state) electric quadrupole transition, performing relativistic many-body calculations of several atomic properties important for optical clock development. All ions discussed are …
Investigating Roles of Triple Excitations for High-precision Determination of Clock Properties of Alkaline Earth Metal Singly Charged Ions
Atomic, Molecular and Optical Physics Division, Physical Research Laboratory（物理研究实验室原子、分子与光学物理分部）；Indian Institute of Technology Gandhinagar（甘地纳加尔印度理工学院）
We demonstrate that several metastable excited states in Hf$~$II, Hf$~$IV and W$~$VI ions may be good clock states since they are sufficiently long-living and are not sensitive to the perturbations. Cooling E1 transitions are available. Energy levels, Landé $g$-factors, transition amplitudes for electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transitions, lifetimes, and electric quadrupole moments for Hf$~$II, Hf$~$IV, and W$~$VI ions are investigated using a combination of several methods of relativistic many-body calculations including the configuration interaction (…
Compact and robust ion traps for thorium are enabling technology for the next generation of atomic clocks based on a low-energy isomeric transition in the thorium-229 nucleus. We aim at a laser ablation loading of single triply ionized thorium in a radio-frequency electromagnetic linear Paul trap. Detection of ions is based on a modified mass spectrometer and a channeltron with single-ion sensitivity. In this study, we successfully created and detected 232Th+ and 232Th2+ ions from plasma plumes, studied their yield evolution, and compared the loading to a quadrupole ion trap with Yb. We explor…
An active optical clock based on highly charged Nd$^{9+}$ ion is proposed for the first time. The clock can offer ultra-narrow linewidth at the $\upmu$Hz-level which is more than two-order of magnitude below the currently recorded laser linewidth. Operating at 605(90) nm superradiation lasing transition between the $5p^2~4f$ ground state and one of the long-lived $5p~4f^2$ excited state, the proposed active clock is inherently immune against the cavity noise which provides high stability. The clock serves as a sensitive probe with high sensitivity to variation of the fine-structure constant wi…
Suppressing inhomogeneous broadening in a lutetium multi-ion optical clock
我们演示了由三个$^{176}$ Lu $^+$离子组成的多离子时钟中的非均匀加宽的精确测量和控制。在$^3D_1$水平的超精细状态之间的微波光谱学被用于测量离子之间的差分系统位移，最显著的是与电四极矩相关的那些。通过适当的磁场排列，我们证明了这些影响的抑制相对于$^1S_0\leftrightarrow{}^3D_1$的光学跃迁频率的$\sim 10^{-17}$水平。光学跃迁的相关光谱证明了在具有相应的投影噪声限制稳定性$σ(τ)=8.2\times 10^{-17}/\sqrtτ$的三离子配置中10 s Ramsey询问的可行性
Attempts are made to unify gravity with the other three fundamental forces of nature. As suggested by higher dimensional models, this unification may require space and time variation of some dimensionless fundamental constants. In this scenario, probing temporal variation of the electromagnetic fine structure constant ($α= \frac{e^2} {\hbar c}$) in low energy regimes at the cosmological time scale is of immense interest. Atomic clocks are ideal candidates for probing $α$ variation because their transition frequencies are measured to ultra-high precision accuracy. Since atomic transition freque…
Sympathetic cooling of $^{113}$Cd$^+$ by laser-cooled $^{40}$Ca$^+$ in a linear Paul trap for Microwave Ion Clocks
本文报道了在线性Paul阱中用激光冷却$^{40}$ Ca $^+$对$^{113}$ Cd $^+$的共振冷却。实现了$^{113}$ Cd $^+$离子的长期低温约束。这些离子的温度测量在$90(10)$ mK，和相应的不确定性所产生的二阶多普勒频移估计为$2\times10^{-17}$的水平。高达$4.2\times10^5$ Cd $^+$离子被限制在阱中，并且测量的限制时间常数为84小时。在约束三小时后，仍然存在$10^5$ Cd $^+$离子，表明这种Ca $^+$ -Cd $^+$双离子体系是令人惊讶的稳定。交流斯塔克位移由钙$^+$激光和荧光诱导，其使用高精度\textit{ab initio}方法小心地估计到$5.4(0.5)\times10^{-17}$的精度。由于死区时间较短，还推导出了Dick-effect限制的Allan偏差。这些结果表明，微波钟的基础上，这种同情冷却计划持有承诺，在提供超高的频率精度和稳定性。
