Revealing the high-redshift Universe with superconducting on-chip spectrometers

宇宙是如何开始的？第一个星系是什么时候形成的？什么是“暗能量”？这些是现代天文学和宇宙学中的一些重大悬而未决的问题。这些问题的答案被编码在物质的分布中，以及它在整个宇宙历史中是如何演变的。这项研究将开发一种新的传感器技术，这将使一类新的天体物理实验成为可能，该实验将探索整个宇宙时间的结构演变。当我们将望远镜对准夜空时，我们观察到来自数百万恒星和星系的光。因为光需要时间传播到我们身边，我们实际上是在回顾时间，通过拍摄夜空的图像，我们能够建立一幅宇宙演化过程中物质分布的历史图景。为了提取关于星系的所有信息，需要测量光线的总亮度和颜色。光谱仪能够将光分成不同的颜色，是构建大型星系星表的关键工具。这些星系调查与宇宙微波背景(CMB)相结合，形成了我们目前对宇宙的起源、内容和演化的理解。尽管有如此丰富的数据，但关于我们的宇宙是如何开始的直接证据以及对暗能量的真正理解仍然难以捉摸。典型的星系调查是使用在光学/红外波长下工作的强大望远镜来建造的。这种波长的选择非常适合附近的星系，只在较晚的时候探测，而相对来说，早期宇宙还没有被发现。宇宙的膨胀改变了遥远星系发出的光，并将波长延伸到亚毫米(Sub-mm)波长范围。这种微弱的亚毫米光的检测带来了许多挑战，并需要与传统半导体阵列完全不同的检测技术。虽然亚毫米单色相机已经有了成熟的解决方案，但亚毫米光谱技术是一个需要专门开发的领域。目前最先进的仪器体积庞大，价格昂贵，通常需要移动部件，难以规模化。该奖学金的主要技术目标将是开发一种新技术，提供一种利用成熟技术的小型化、低成本解决方案。这项技术的关键是在单个硅片上沉积精细调谐的超导集成电路的组合。随着超导电路的光刻定义，整个光谱仪可以在一平方厘米的硅上实现；这一功能以前需要一台尺寸接近一米的仪器。尺寸和成本的显著降低将使构建具有数千个光谱仪的2D阵列成为可能，在从最初的概念验证设备中获得的传统和经验的基础上，该奖学金将开发、演示和优化能够在整个亚毫米波长范围内运行的可扩展芯片上超导光谱仪。在这项研究中，墨西哥50米大毫米望远镜的专门演示为促进这项新技术的成熟度提供了一个独特的机会，如果成功，将开启一种新的星系调查类别，目标是我们宇宙中最早的星系，补充现有的光学/红外星系调查。事实上，这些技术的结合将作为重要的系统交叉检查，而调查之间的相互关联有望成为进一步改善对宇宙学参数的限制的有力方法。

How did the Universe begin? When did the first galaxies form? What is "dark energy"? These are some of the major outstanding questions in modern astronomy and cosmology. The answers to these questions are encoded in the distribution of matter and how it has evolved throughout the history of the Universe. This fellowship will develop a novel sensor technology that will enable a new class of astrophysical experiments that will probe of the evolution of structure throughout cosmic time.When we point our telescopes toward the night sky, we observe light that originates from millions of stars and galaxies. Because light takes time to travel to us, we are effectively looking back in time, and by taking images of the night sky we are able to build up a picture of the history of distribution of matter as the Universe evolved. To extract all the information about a galaxy, a measure of the total brightness and the colour of the light is needed. Spectrographs are able to separate light into colours, and are a key tool that can be used to construct large catalogues of galaxies. These galaxy surveys, in combination with the cosmic microwave background (CMB), have shaped our current understanding of the origin, content, and evolution of the Universe. Despite this wealth of data, direct evidence of how our Universe began and a true understanding of dark energy remain elusive. Typical galaxy surveys are built using powerful telescopes that operate at optical/infrared wavelengths. This choice of wavelength is well suited to nearby galaxies, probing only late times whilst leaving the early Universe relatively undiscovered. The expansion of the Universe modifies the light emitted from very distant galaxies and stretches the wavelength into the sub-millimetre (sub-mm) wavelength range. Detection of this faint sub-mm light poses a number of challenges and requires a fundamentally different detection technology to traditional semiconductor arrays. While mature solutions exist for sub-mm single-colour cameras, technology for sub-mm spectroscopy is an area requiring dedicated development. Current state-of-the art instruments are bulky and expensive, often requiring moving parts that are challenging to scale. The main technical objective of this fellowship will be to develop a novel technology that provides a miniaturised, low-cost solution that takes advantage of well-established techniques. The key to this technology is a combination of finely tuned superconducting integrated circuits deposited on a single silicon wafer. With superconducting circuits defined lithographically, an entire spectrometer can be realised on a square centimetre of silicon; this functionality would previously have required an instrument close to a metre in size. The significant reduction in size and cost will enable the construction of 2D arrays with thousands of spectrometers, and building on the heritage and experience gained from initial proof-of-concept devices, this fellowship will develop, demonstrate, and optimise scalable on-chip superconducting spectrometers capable of operating over the entire sub-mm wavelength range. A dedicated demonstration at the Mexican 50-m Large Millimetre Telescope within this fellowship offers a unique opportunity to boost the maturity of this novel technology, and success would open up a new class of galaxy surveys that target the earliest galaxies in our Universe, complementing existing optical/infrared galaxy surveys. In fact, the combination of these techniques would serve as important systematic cross-checks, and cross-correlations between the surveys promise to be a powerful approach to further improve constraints on cosmological parameters.