Towards local measurements of space-time geometries with optical clocks

利用光学时钟对时空几何进行局部测量

• 批准号: 436207576
• 负责人: Professor Dr. Daniel Braun
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/436207576?language=en
• 关键词: Towards; local; measurements; space; time

The goal of the proposal is to develop proposals for experiments with which non-trivial space-time geometries can be measured locally, i.e. in a lab or with a satellite experiment, by using optical clocks. So far it is theoretically and even more so observationally unclear whether the global structure of space-time that describes the global expansion of the Universe is relevant in our local astronomical environment. But meanwhile, optical clocks achieve precisions that should make it possible in principle to measure Hubble´s constant that describes the expansion of the Universe on large scales in interference experiments. It is towards such kind of experiments that we want to work with theoretical analyses. To that end we will analyze three different kinds of situations: 1. The frequency shift of an optical resonator; 2. A satellite experiment similar to LISA (Laser Interferometer Space Antenna), the space-based gravitational wave detector that is currently being constructed; and 3. A fiber-optical experiment in which a phase-boundary created by a non-linear pulse moves with the speed of light in the fiber and is measured with a probe pulse. These three physical systems will be embedded in the McVittie metric, the simplest metric in which a gravitational central potential is superposed on an expanding space-time, and which represents one of the original proposals for our local space-time in the expanding Universe. Besides experiments with classical optics we also want to investigate possibilities whether multi-mode quantum metrology can help to measure the expected very small effects. We will also investigate whether with these setups other interesting gravitational effects can be measured, such as the presence of dark matter or geophysical effects, as e.g. terrestrial motion of matter (atmospheric and ocean currents, motion of tectonic plates). Applications for the synchronization of optical clocks via optical-fiber networks will be considered.

该提案的目标是为可以在局部测量非平凡时空几何形状的实验提出建议，即在实验室或卫星实验中使用光学时钟。到目前为止，描述宇宙整体膨胀的时空整体结构是否与我们当地的天文环境相关，在理论上甚至在观测上都还不清楚。但与此同时，光学时钟达到的精度，原则上应该可以在干涉实验中测量哈勃常数，该常数描述了宇宙在大尺度上的膨胀。正是针对这样的实验，我们想要进行理论分析。为此，我们将分析三种不同的情况：光谐振器的频移；2. 类似于LISA（激光干涉仪空间天线）的卫星实验，LISA是目前正在建造的天基引力波探测器；和3。一种光纤实验，由非线性脉冲产生的相位边界在光纤中以光速运动，并用探针脉冲测量。这三个物理系统将嵌入麦克维蒂度规中，这是最简单的度规，其中引力中心势叠加在膨胀的时空上，它代表了我们在膨胀的宇宙中局部时空的原始建议之一。除了经典光学实验外，我们还想研究多模量子计量是否可以帮助测量预期的非常小的效应。我们还将研究这些装置是否可以测量其他有趣的引力效应，例如暗物质的存在或地球物理效应，例如物质的地球运动（大气和洋流，构造板块的运动）。将考虑通过光纤网络实现光时钟同步的应用。