A Quantum Jump Sensor for Dark Matter Detection

用于暗物质检测的量子跃迁传感器

• 批准号: ST/W006650/1
• 负责人: Jack Devlin
• 金额: $ 59.4万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FW006650%2F1
• 关键词: Quantum; Jump; Sensor; Dark; Matter

It is remarkable that on a cosmic scale, we do not know what makes up 84% of the matter in the universe. This dark matter has a profound impact on the movement of stars, the formation of galaxies and the patterns in the afterglow of the Big Bang, but we can only hypothesise what its true nature might be. We will build a new type of quantum sensor using a single isolated electron that will be sensitive enough to tell if dark matter is made from certain types of new particles.It seems likely that most of the missing matter is some new type of substance which barely interacts with ordinary matter electromagnetically. One hint for what this might be comes from the differing symmetries of the strong and weak nuclear forces, which led particle physicists to propose a new particle, the axion. The theory which predicted the axion does not predict its mass, but light axions around 10^9-10^12 times less than the mass of an electron would have been created in the early universe and still be present today as dark matter.As well as hints from particle physics, there are also indications from cosmology as to the properties of dark matter. Observations of the microwave transition frequencies of hydrogen in the period of the early universe known as the cosmic dawn suggest that it was colder than expected. This was also the period where dark matter could collide with ordinary mater and reduce its temperature. Exotic particles with tiny charges - known as millicharged particles - would account for this observation. Many experiments have been carried out to detect axions and millicharged particles, but none have been discovered. The most sensitive experiments to detect axions use a strong magnetic field to encourage the axions to decay into microwave photons with a frequency directly related to the axion mass. They then detect those microwaves. Unfortunately, for an important axion mass range, state-of-the art microwave detectors have a fundamental and unavoidable noise source which dwarfs the axion signal. This minimum noise, referred to as the Standard Quantum Limit can be overcome by counting the number of photons which make up the electromagnetic field. No suitable single photon counter exists in the range 30-60 GHz, so we will invent one. The technology we have chosen is a single electron, trapped in a combination of electric and magnetic fields. As the electron absorbs a microwave photon, its quantum orbit changes detectably. A trapped electron is also sensitive to collisions with any millicharged dark matter, also changing its orbit after a collision. This change in orbit can be measured using quantum jump spectroscopy, which was previously used to measure the electron's magnetic moment.If we could uncover the nature of dark matter, we would finally have understood the most abundant substance in the universe and characterising its precise properties would have implications for many aspects of astrophysics. A discovery of the axion or millicharged particle would only be the start of a new era of particle physics since both particles would be expected to be accompanied by others. In the case of the axion, these could be much heavier Higgs particles, giving an additional strong argument for the construction of a Future Circular Collider at CERN to discover them. Finally, this device is a sensor for the weakest detectable microwave signals, which could be applied to improved microwave astronomy, molecular spectroscopy for the identification of chemical substances and sensing.

值得注意的是，在宇宙尺度上，我们不知道宇宙中 84% 的物质是由什么组成的。这种暗物质对恒星的运动、星系的形成以及大爆炸余辉的模式有着深远的影响，但我们只能假设它的真实本质是什么。我们将使用单个孤立电子构建一种新型量子传感器，该传感器足够灵敏，可以判断暗物质是否是由某些类型的新粒子制成的。 看起来大部分缺失的物质可能是某种新型物质，它们几乎不存在。与普通物质发生电磁相互作用。关于这可能是什么的一个暗示来自强核力和弱核力的不同对称性，这导致粒子物理学家提出了一种新粒子：轴子。预测轴子的理论并没有预测它的质量，但是比电子质量小 10^9-10^12 倍左右的光轴子可能是在早期宇宙中产生的，并且今天仍然以暗物质的形式存在。作为粒子物理学的线索，宇宙学也对暗物质的性质提供了线索。在被称为宇宙黎明的早期宇宙时期，对氢的微波跃迁频率的观测表明，它比预期的要冷。这也是暗物质可以与普通物质碰撞并降低其温度的时期。带有微小电荷的奇异粒子（称为毫带电粒子）可以解释这一观察结果。人们进行了许多实验来检测轴子和毫带电粒子，但都没有被发现。检测轴子的最灵敏的实验使用强磁场来促使轴子衰变成微波光子，其频率与轴子质量直接相关。然后他们检测这些微波。不幸的是，对于重要的轴子质量范围，最先进的微波探测器具有基本且不可避免的噪声源，该噪声源使轴子信号相形见绌。这种最小噪声（称为标准量子极限）可以通过计算构成电磁场的光子数量来克服。 30-60 GHz 范围内不存在合适的单光子计数器，因此我们将发明一个。我们选择的技术是单个电子，被困在电场和磁场的组合中。当电子吸收微波光子时，其量子轨道会发生可检测到的变化。被捕获的电子对与任何毫电荷暗物质的碰撞也很敏感，碰撞后也会改变其轨道。这种轨道的变化可以使用量子跃迁光谱来测量，量子跃迁光谱以前用于测量电子的磁矩。如果我们能够揭示暗物质的本质，我们最终将了解宇宙中最丰富的物质并表征其精确性质将对天体物理学的许多方面产生影响。轴子或毫带电粒子的发现只会是粒子物理学新时代的开始，因为这两种粒子都预计会伴随着其他粒子。就轴子而言，这些粒子可能是重得多的希格斯粒子，这为欧洲核子研究中心建造未来圆形对撞机来发现它们提供了额外的有力论据。最后，该设备是一种可检测到的最弱微波信号的传感器，可应用于改进的微波天文学、化学物质识别和传感的分子光谱学。