Differential atom interferometry and velocity selection using the clock transition of strontium atoms for AION

该计划开发的技术将通过开发和实施时钟激光技术以及测试超长基线仪器的方法，增强原子干涉测量观测网（AION）和MAGIS-100项目中的原子干涉测量。开发新一代量子传感器的强大科学动机源于详细的理论工作，这些工作表明这些仪器将如何推动对某些类型暗物质的搜索超越当前的边界，并开创了一种新的方法来探测与现有实验不同频率范围的引力波LIGO和Virgo（从而补充现有方法）。世界各地的长基线原子干涉仪将联网，通过联合观测有许多可能的协同作用。虽然地球上的引力波探测提供了丰富的新信息，但在太空中可以实现更高的灵敏度，未来的项目，如暗物质原子实验和空间重力探测（AEDGE），已经在讨论中。AION仪器结合了基于Sr原子和原子干涉测量的最先进光学时钟的优点。两团原子云将沿着一条垂直的长真空管道在不同的高度上形成，两团原子云都将被发射出去，这样它们就会向上移动，然后在重力作用下停止并回落。这种“原子喷泉”允许很长的测量时间，但原子必须冷却到低于1纳米开尔文的温度，否则它们在回落到检测区域之前会扩散得太多。一个垂直的激光束以不同的高度穿过两个原子云，这样就有了通过差分测量对噪声的共模抑制。目前正在开发所需技术的某些方面。在这个建议中，我们将开发使用原子锶中最窄的单光子跃迁的干涉仪所需的窄带宽（几赫兹）激光系统；在（698nm）处的时钟跃迁比最初计划用于微分干涉测量的初始演示器（689nm）的跃迁窄1000倍。这种电子和光学技术将作为可靠的模块开发，以便将来在大型基线仪器的现场部署。这是迈向AION-10装置的重要一步。此外，窄的时钟跃迁允许极其精确的速度选择原子的分布，需要从一个长干涉仪序列的高对比度条纹。此外，这允许通过从单个传输原子云中顺序选择不同速度等级来快速交错干涉测量序列，而无需重复激光冷却和传输过程。这项工作将得到AION正在开发的高效数值技术的综合模拟的支持。AION项目利用STFC和EPSRC在量子技术、计算和计量等战略领域之间的协同效应。它汇集了一个由实验和理论粒子物理学家、天体物理学家和仪器专家、量子信息科学家、基于Sr的原子钟研究专家以及来自STFC和EPSRC社区的原子物理学家组成的联盟。AION的量子技术在导航和石油钻探等各个领域都有潜在的应用。我们将与英国量子技术中心在传感器和计量方面密切合作，开发这些技术并将其推向市场。

The technology developed in this programme will enhance atom interferometry in both the Atom Interferometry Observatory Network (AION) and MAGIS-100 projects by developing and implementing clock-laser technology and test of the methodology for very long baseline instruments. The strong scientific motivation for developing a new generation of quantum sensors stems from detailed theoretical work that shows how these instruments will push searches for certain types of dark matter beyond current boundaries and pioneer a new approach to the detection of gravity waves in a different range of frequency from the existing experiments LIGO and Virgo (thus complementing existing approaches). The long-baseline atom interferometers around the world will be networked, and there are many possible synergies through joint observations. Although gravity-wave detection on Earth provides a wealth of new information, much higher sensitivity can be achieved in space and future projects such as the Atomic Experiment for Dark Matter and Gravity Exploration in Space (AEDGE), are already being discussed.The AION instrument combines the advantages of state-of-the-art optical clocks based on Sr atoms with atom interferometry. Two clouds of atoms will be prepared at different heights along a long vertical vacuum pipe, and both clouds will be launched so that they travel upwards before coming to rest and falling back down under gravity. Such 'atomic fountains' allow a long measurement time but atoms must be cooled to temperatures less than 1 nanokelvin otherwise they spread out too much before falling back through the detection region. A vertical laser beam runs through both clouds of atoms, at different heights, so that there is common-mode rejection of noise by differential measurement.Some aspects of the required technology are being developed. In this proposal, we shall develop the narrow bandwidth (few Hz) laser systems required for an interferometer using the narrowest single-photon transition in atomic strontium; the clock transition at (698nm) which is 1000 times narrower than the transition (at 689nm) originally planned for the initial demonstrator of differential interferometry. This electronic and optical technology will be developed as reliable modules for future deployment at the site of large baseline instruments. This represents an important stepping stone towards the AION-10 device. In addition, the narrowness of the clock transition allows extremely precise velocity selection of atoms from a distribution as required for high-contrast fringes from a long interferometer sequences. Furthermore this allows rapid interleaving of interferometry sequences by the sequential selection of different velocity classes from a single transported atom cloud, without repeating the laser cooling and transport processes. This work will be supported by comprehensive simulations using efficient numerical techniques being developed in AION. The AION programme exploits synergies between STFC and EPSRC science and the strategic areas of quantum technology, computing and metrology. It brings together a consortium of experimental and theoretical particle physicists, as well as astrophysicists and instrumentation experts, quantum information scientists, experts in Sr based atomic-clock research, and atomic physicists drawn from the STFC and EPSRC communities. The quantum technologies of AION have potential applications in such varied areas as navigation and oil drilling. We will work closely with the UK Quantum Technologies Hub in sensors and metrology to develop these technologies and bring them to market.