论文标题
使用量子非解析测量来改善光原子时钟的Q因子
Improving the Q factor of an optical atomic clock using quantum non-demolition measurement
论文作者
论文摘要
量子非解析（QND）测量是操纵量子系统的非凡工具。它允许提取特定信息，同时仍保留系统的脆弱量子可观察到。在这里，我们将基于空腔的QND测量应用于光学晶格时钟---一种具有无与伦比的频率精度的一种原子时钟---以80 \％的保真度读数后原子的量子相干性。我们将此技术应用于通过一系列重复的QND测量值稳定超高激光的相位。我们利用拉姆西光谱时间从300〜ms到2〜s来利用超高激光的提高相位相位来询问单独的光学晶格时钟。使用此技术，我们保持95 \％的对比度，并观察到时钟的\ emph {q}因子增加了七倍，达到$ 1.7 \ times10^{15} $。
Quantum non-demolition (QND) measurement is a remarkable tool for the manipulation of quantum systems. It allows specific information to be extracted while still preserving fragile quantum observables of the system. Here we apply cavity-based QND measurement to an optical lattice clock---a type of atomic clock with unrivalled frequency precision---preserving the quantum coherence of the atoms after readout with 80\% fidelity. We apply this technique to stabilise the phase of an ultrastable laser to a coherent atomic state via a series of repeated QND measurements. We exploit the improved phase-coherence of the ultrastable laser to interrogate a separate optical lattice clock, using a Ramsey spectroscopy time extended from 300~ms to 2~s. With this technique we maintain 95\% contrast and observe a seven-fold increase in the clock's \emph{Q} factor to $1.7\times10^{15}$.
