An optical frequency comb to support the quantum technology for fundamental physics programme

尽管在理解自然的最基本层面上取得了巨大的成功，从宇宙中最微小的组成部分到最大的结构，我们的知识仍然存在巨大的差距。我们不理解量子水平上的引力。宇宙中的大部分物质都是一些看不见的未知物质，我们称之为暗物质。宇宙的膨胀正在加速，由某种未知的力量驱动，我们称之为暗能量。有许多关于量子引力、暗物质和暗能量的理论，但很少有实验证据支持它们或区分它们。基于量子科学和技术最新发展的几项新实验旨在揭示这些奥秘。例如，许多量子引力、暗物质和暗能量的理论预测，自然界的基本常数，如电子质量除以质子质量，实际上应该在空间或时间中变化。这一预测可以通过比较不同原子和分子的不同时钟的滴答声来测试，并观察它是否会随着时间的推移而变化。英国正在建设一个这样的精密时钟网络，这些时钟发展得很好。为了比较不同的时钟，我们需要一个关键的设备。这种设备被称为光频梳，它是一种激光器，可以发射出数千个频率分量，这些频率分量的间隔非常均匀。每个分量的频率都可以非常精确地确定。这个工具告诉我们一个时钟的频率如何与另一个时钟的频率进行比较，以及这个频率比是否随时间而变化。值得注意的是，在频率梳的帮助下，时钟甚至不需要在同一位置-它们可以在光纤网络中进行比较。这项提议的目的是获得频率梳，以便我们正在建立的量子技术能够发挥其潜力，测试基础物理学的基础，并发现超出我们现有知识范围的东西。

Despite the tremendous successes in understanding Nature at its most fundamental level, from the tiniest constituents to the largest structures in the Universe, there remain great gaps in our knowledge. We do not understand gravity at the quantum level. Most of the matter in the Universe is some invisible and unknown substance that we call dark matter. And the expansion of the Universe is accelerating, driven by some unknown force that we call dark energy. There are many theories of quantum gravity, dark matter and dark energy, but little experimental evidence to support them or distinguish between them. Several new experiments based on the latest developments in quantum science and technology aim to shed light on these mysteries. For example, many theories of quantum gravity, dark matter and dark energy predict that fundamental constants of nature, such as the electron mass divided by the proton mass, should actually vary in space or time. This prediction can be tested by comparing the tick rate of different clocks, based on different atoms and molecules, and looking to see whether this changes over time. A network of such precise clocks is being built in the UK, and these clocks are developing well. There is a crucial piece of equipment we need in order to compare different clocks. This equipment is known as an optical frequency comb. It is a laser that emits thousands of frequency components that are perfectly uniformly spaced. The frequency of every component can be determined to extremely high precision. This is the tool that tells us how the frequency of one clock compares to the frequency of another, and whether this frequency ratio is changing over time. Remarkably, with the help of the frequency comb, the clocks do not even need to be at the same location - they can be compared across an optical fibre network. The aim of this proposal is to acquire the frequency comb so that the quantum technologies we are building can fulfil their potential for testing the foundations of fundamental physics and discovering what lies beyond the limits of our current knowledge.