We investigate the cost of three phase estimation procedures that require only constant-precision phase shift operators. The cost is in terms of the number of elementary gates, not just the number of measurements. Faster phase estimation requires the minimal number of measurements with a \log * factor of reduction when the required precision n is large. The arbitrary constant-precision approach (ACPA) requires the minimal number of elementary gates with a minimal factor of 14 of reduction in comparison to Kitaev's approach. The reduction factor increases as the precision gets higher in ACPA. Kitaev's approach is with a reduction factor of 14 in comparison to the faster phase estimation in terms of elementary gate counts.
Enhancing the estimation precision of an unknown phase shift in multipartite Glauber coherent states via skew information correlations and local quantum Fisher information
Precision isotope shift measurements in Ca$^+$ using highly sensitive detection schemes
我们展示了一种有效的高精度光谱技术，为单囚禁离子与非封闭的过渡。在双搁置技术中，单个光子的吸收首先被放大到与不同种类的共捕获冷却离子共享的正常运动模式的几个声子，然后使用标准电子搁置技术被进一步放大到由冷却离子发射的数千个荧光光子。我们采用这种扩展的光子反冲光谱技术进行第一次高精度的绝对频率测量的$^{2}$ D $_{3/2}$ $\rightarrow$ $^{2}$ P $_{1/2}$过渡的$^{40}$钙$^{+}$，导致在$f=346\, 000\, 234\, 867(96)$ kHz的过渡频率。此外，我们确定了该跃迁的同位素位移和$^{2}$ S $_{1/2}$ $\rightarrow$ $^{2}$ P $_{1/2}$跃迁的$^{42}$ Ca $^{+}$，$^{44}$ Ca $^{+}$和$^{48}$ Ca $^{+}$离子相对于$^{40}$ Ca $^{+}$的精确度低于100 kHz。改进的场和质量移动常数的这些过渡，以及在均方核电荷半径的变化提取从这个高分辨率的数据。
Quantum-limited estimation of the frequency shift between two interfering photons by time sampling of their quantum beats
University of Portsmouth（朴茨茅斯大学）；Politecnico di Bari（巴里理工大学）；INFN, Sezione di Bari（意大利国家核物理研究所巴里分部）；Institute of Cosmology and Gravitation, University of Portsmouth（朴茨茅斯宇宙学与引力研究所）
Precision probing of ionic-core transitions in alkaline-earth Rydberg atoms
Graduate School of Engineering Science, The University of Osaka（大阪大学工学研究科）；Center for Quantum Information and Quantum Biology, The University of Osaka（大阪大学量子信息与量子生物学中心）
Oscillating quadrupole effects in high precision metrology
从理论上研究了振荡四极场对原子能级的影响，给出了四极矩阵元的一般表达式。结果是相关的任何基于离子的时钟，其中一个时钟状态支持四极矩。估计$^{176}$ Lu $^+$的时钟偏移，并表明耦合到四极场不会限制时钟精度在$\lesssim10^{-19}$水平。然而，建议一种方法，将允许这种转变进行校准。这种方法利用共振四极耦合，使四极矩的原子被测量。使用$^{138}$ Ba $^+$给出了原理证明，其中$D_{5/2}$态的四极矩估计为$Θ=3.229(89) e a_0^2$。
