CAREER: Operating an Optical Atomic Clock Beyond the Laser Coherence and below the Projection Limit

光学原子钟是人类最精确的计量工具，其分数不稳定性在10^-18级。这相当于在整个宇宙的年龄中损失了不到一秒。这样的精确度不仅使计时精度难以置信，而且还有助于研究可能影响时间流逝的现象，如引力、暗物质和基本常数的变化。未来几代光学原子钟的研究重点是进一步提高精度和/或允许在实际环境中运行的部署系统中实现相当的精度。这项工作将借鉴量子信息科学的工具箱，通过使用在量子纠错中发现的动态措施和使用可编程纠缠生成来提高光学时钟的资源效率。这项研究将为本科生和研究生提供精密计量和原子量子科学的实践经验。这种经验，以及课程创新和向更广泛社区的推广，将有助于促进美国量子劳动力的增长和多样性。光学时钟的工作原理包括将亚赫兹线宽激光振荡器与超窄原子跃迁进行比较，以纠正其频率波动和漂移。时钟性能的主要限制来自(1)激光振荡器的基线稳定性，以及(2)校正激光频率波动所需的原子资源，其准确性受到量子测量的投影性质的阻碍。这项工作试图通过在同一设备内实现两个原子阵列光学时钟的独立操作，以及通过使用光学腔来设计自旋压缩以减轻投影噪声来解决这两个问题。具体来说，通过利用镱-171的丰富原子结构，一个时钟子系统将通过“中路”操作在另一个时钟子系统的查询期间用于实时校正激光相位，从而使激光相干时间延长近10倍。这项工作将中性原子量子计算机、光学原子钟和量子网络设备的功能融合到一个系统中。因此，它将导致广泛的社会影响的进步，如容错量子处理器以及光学原子钟的量子网络，可以提供量子安全计时和搜索新物理的能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Optical atomic clocks are mankind’s most accurate metrological tool with fractional instabilities at the 10^-18 level. This corresponds to losing less than one second in the entire age of the universe. Such accuracy not only enables incredible timing precision, but also facilitates the study of phenomena that may affect the passage of time such as gravity, dark matter, and the variation of fundamental constants. Research on future generations of optical atomic clocks is focused on further improving accuracy and/or allowing a comparable accuracy to be achieved in deployed systems operating in real-world environments. This work will draw from the toolbox of quantum information science to improve the resource efficiency of optical clocks by using on-the-fly measures such as those found in quantum error correction and by using programmable entanglement generation. This research will provide undergraduate and graduate students with hands-on experience in precision metrology and atomic quantum science. This experience, along with curricular innovations and outreach to the broader community, will help promote the growth and diversity of the American quantum workforce.The operating principle of optical clocks involves comparing a sub-Hz-linewidth laser oscillator to an ultra-narrow atomic transition to correct its frequency fluctuation and drift. The main limitations on clock performance stem from (1) the baseline stability of the laser oscillator, and (2) the atomic resources needed to correct laser frequency fluctuations whose accuracy is hampered by the projective nature of quantum measurements. This work seeks to address both issues by enabling independent operation of two atomic array optical clocks within the same apparatus and by using an optical cavity to engineer spin squeezing that mitigates projection noise. Specifically, by levering the rich atomic structure of ytterbium-171, one clock subsystem will be used for real-time correction of the laser phase during the interrogation of the other clock subsystem via ‘mid-circuit’ operations, enabling nearly a 10-times extension beyond the laser coherence time. This work merges the capabilities of neutral-atom quantum computers, optical atomic clocks, and quantum networking devices into one system. It will thus lead to advances of broad societal impact such as fault-tolerant quantum processors as well as quantum networks of optical atomic clocks that can provide quantum-secured timekeeping and the ability to search for new physics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.