Extension to the 'Quantum-enhanced Interferometry for New Physics' programme

现代物理学解释了从最小尺度到最大尺度的各种惊人的现象，并且已经彻底改变了世界！激光、半导体和晶体管是我们的笔记本电脑、移动电话和医疗设备的核心。这些技术反过来又使我们能够更详细、更精确、更严格地探索自然世界。在过去的几年里，英国和世界各地的国家量子技术计划正在开发新的量子技术，这些技术可能会影响我们的日常生活，并使基础物理研究能够带来新的发现。光的量子态最近提高了引力波探测器的灵敏度，迄今为止，引力波探测器的探测已经吸引了公众，超导过渡边缘传感器现在被用于捕捉宇宙高分辨率图像的望远镜中。尽管现代物理学取得了这些成功，但仍有几个深刻而具有挑战性的问题尚未解决。我们的联盟QI扩展将基于量子技术的最新进展，在我们现有的联盟QI和之外，解决两个最紧迫的问题：(i)暗物质的本质是什么，（ii）如何将量子力学与爱因斯坦的相对论结合起来？第一个研究方向是由大量的观测所推动的，这些观测表明，星系中有很大一部分物质是光学望远镜无法直接观测到的。了解这种神秘的所谓暗物质的本质将揭示宇宙的历史，并将引发基础物理学和应用物理学的新研究领域。世界范围内许多最先进的实验都在寻找暗物质的候选者，但到目前为止还没有运气。我们建议寻找的候选者是轴子和类轴子粒子（ALPs）。这些粒子是由粒子物理学中悬而未决的问题所激发的，它们可能是暗物质的重要组成部分或全部。首先，我们将提高当前实验的灵敏度，以探测暗物质信号，或者在大范围的轴子质量下，将现有的轴子-光子耦合限制提高几个数量级。其次，我们将建立并表征一个大型（8英寸/200纳米直径）超导纳米线单光子探测器，以扩展暗物质搜索。我们的第二个研究方向是空间和时间的本质。我们有一长串关于量子力学和爱因斯坦相对论的成功实验测试。但是引力应该和量子力学结合起来吗？如果有，怎么做？就像物理学中任何悬而未决的问题一样，实验可以指引我们找到答案。为此，我们建议研究时空的两个量子方面。首先，我们将实验研究全息原理，该原理表明体积的信息内容可以编码在其边界上。我们将利用光的量子态，建造两个超灵敏的激光干涉仪，以前所未有的灵敏度研究空间不同区域之间可能的相关性。我们还将利用这些数据在星系晕中寻找标量暗物质。其次，我们将寻找近似解决量子引力问题的半经典引力模型的特征。在现有的半经典引力模型实验测试的基础上，我们将寻求设计桌面实验，以提供引力量子本质的直接特征。在现代量子技术的帮助下，回答这些具有挑战性的基础物理学问题，有可能为物理学研究开辟新的视野，并达到对我们生活的世界的理解的新水平。所提出的研究方向共享量子增强干涉测量的共同技术平台，并受益于所涉及的研究人员的不同技能。

Modern physics explains a stunning variety of phenomena from the smallest of scales to the largest and has already revolutionized the world! Lasers, semiconductors, and transistors are at the core of our laptops, mobile phones, and medical equipment. These technologies in turn have enabled us to explore the natural world with ever greater detail, precision, and rigour.Over the last few years, novel quantum technologies are being developed within the National Quantum Technology Programme in the UK and throughout the world that could impact our everyday lives and enable fundamental physics research that leads to new discoveries. Quantum states of light have recently improved the sensitivity of gravitational-wave detectors, whose detections to date have enthralled the public, and superconducting transition-edge-sensors are now used in telescopes that capture high-resolution images of the universe.Despite these successes of modern physics, several profound and challenging questions remain open. Our consortium QI-extension will build on recent advances in quantum technologies, both within our existing consortium QI and beyond, to address two of the most pressing questions: (i) What is the nature of dark matter, and (ii) How can quantum mechanics be united with Einstein's theory of relativity?The first research direction is motivated by numerous observations which suggest that a significant fraction of the matter in galaxies is not directly observed by optical telescopes. Understanding the nature of this mysterious so-called dark matter will shed light on the history of the universe and will trigger new areas of research in fundamental and possibly applied physics. A number of state-of-the-art experiments world-wide are looking for dark matter candidates with no luck so far. The candidates we propose to search for are axions and axion-like-particles (ALPs). These particles are motivated by outstanding questions in particle physics and may account for a significant part, or all of dark matter. First, we will enhance the sensitivity of our current experiment that will detect a dark matter signal or improve the existing limits on the axion-photon coupling by a few orders of magnitude for a large range of axion masses. Second, we will build and characterise a large (8''/200 nm diameter) superconducting nanowire single photon detector to extend dark matter searches.Our second line of research is devoted to the nature of space and time. We have a long list of successful experimental tests of quantum mechanics and Einstein's theory of relativity. But should gravity be united with quantum mechanics? If so, how? As with any open question in physics, experiments can direct us towards the answers.To that end, we propose to study two quantum aspects of space-time. Firstly, we will experimentally investigate the holographic principle, which states that the information content of a volume can be encoded on its boundary. We will exploit quantum states of light and build two ultra-sensitive laser interferometers that will investigate possible correlations between different regions of space with unprecedented sensitivity. We will also use the data to search for scalar dark matter in the galactic halo.Secondly, we will search for signatures of semiclassical gravity models that approximately solve the quantum gravity problems. Building on our existing work on experimentally testing semiclassical models of gravity, we will seek to design table-top experiments that may provide direct signatures of the quantum nature of gravity.Answering these challenging questions of fundamental physics with the aid of modern quantum technologies has the potential to open new horizons for physics research and to reach a new level of understanding of the world we live in. The proposed research directions share the common technological platform of quantum-enhanced interferometry and benefit from the diverse skills of the researchers involved.