Optical clocks based on an ensemble of trapped ions

拟议的科学项目是基于德国科学研究协会（DFG）和俄罗斯基础研究基金会（RFBR）之间的合作谅解备忘录。我们要求在新西伯利亚激光物理研究所（PI: Sergei Bagayev教授）和德国物理技术研究所（PI: T.E.博士Mehlstäubler）之间进行为期两年的科学交流。俄罗斯合作伙伴将同时向RFBR提交一份单独的研究提案。在这次科学交流和合作中，我们将开发用于捕获离子扩展集合的精密光谱的实验和理论工具。将调查两个方面。在工作包1中，我们将评估新西伯利亚公司自建的激光系统对In+离子高精度光谱的适用性。在工作包2中，我们将解决In+和Yb+离子混合晶体中多离子方法精度的最终限制问题，并为未来扩展到询问纯Yb+离子系综中高度禁止的八极跃迁提出想法。该项目开发的工具将为实现基于in +和Yb+离子的多离子时钟铺平道路。我们的方法可以超越当今最好的光学离子钟的性能。我们期望这将是离子钟的实用性和应用的重要一步。这将直接影响光学钟的基础物理测试，以及它们作为相对论大地测量的量子传感器的应用。

The proposed scientific project is based on the memorandum of understanding on cooperation between the Deutsche Forschungsgemeinschaft (DFG) and the Russian Foundation for Basic Research (RFBR). We ask for support of a scientific exchange between the Institute for Laser Physics - ILP, Novosibirsk (PI: Prof. Sergei Bagayev), and the Physikalisch Technische Bundesanstalt - PTB (PI: Dr. T.E. Mehlstäubler) for the duration of two years. The Russian partner will submit a separate research proposal to RFBR in parallel. During this scientific exchange and collaboration we will develop experimental and theoretical tools for precision spectroscopy in an extended ensemble of trapped ions. Two aspects will be investigated. In work package 1 we will evaluate a self-built laser system from Novosibirsk for its suitability for high-precision spectroscopy in In+ ions. In work package 2 we will address the question of ultimate limits in accuracy of the multi-ion approach in a mixed-species crystal of In+ and Yb+ ions and develop ideas for a future extension to interrogating the highly-forbidden octupole transition in a pure ensemble of Yb+ ions. The tools developed in this project will pave the way to realize a multi-ion clock based on In+ and Yb+ ions. Our approach can surpass the performance of todays best optical ion clocks. We expect that this will be a major step towards the practicability and application of ion clocks. This will directly affect tests of fundamental physics with optical clocks as well as their application as quantum sensors for relativistic geodesy.