compact Cold-Atom Sources (cCAS)

开发碱金属铷、铯、钾的紧凑型冷原子源；碱土金属锶（Sr）。这些都非常适合于量子技术的一系列应用，以及更广泛地用于科学研究的设备构建中的组件。磁光阱（MOTs）可以在室温下直接从原子蒸气中捕获慢原子，为冷原子提供了一个非常方便的来源。多年来，我们在三个独立的实验中使用了在真空区域内排列成金字塔的四个三角形镜子来制作MOT。最近，我们开发了一种改进的设计，比其他来源更紧凑和可调。2016年4月，我们申请了一项专利，该专利涵盖了这个金字塔- mot的创新功能，我们正在构建一个使用铷（Rb）的原型。我们将把它开发成与M Squared激光器（MSL）生产的激光系统集成的商业产品。该公司的掺钛蓝宝石激光器提供了高功率，相对于其他可调谐激光器，和无与伦比的稳定性。我们将通过调整反射镜的尺寸和封闭真空室来充分利用可用的激光功率，以产生高通量的原子。这将在诸如原子干涉仪之类的仪器中提供强信号和高重复测量率，而原子干涉仪是重力仪、陀螺仪等中使用的量子技术的基础。该装置可以激光冷却其他碱金属原子Cs和K，所需的所有波长的光都可以从MSL获得。紧凑可靠的冷原子源本身就是一种有用的设备，可以在构成MSL目前销售的大部分科学设备市场上销售。在研究紧凑型冷原子源时，我们注意到人们对将冷锶原子用于光学晶格钟、物质波干涉仪和超冷量子气体实验的兴趣迅速增加。锶具有固有的优势，如快速激光冷却，对外部磁场不敏感，对于某些同位素，原子间碰撞几乎可以忽略不计。然而，使用冷的Sr原子比Rb原子在技术上要求更高。在传统的激光冷却方法中，这种锶原子沿着锥形螺线管的轴线传递（所谓的塞曼减速在20世纪80年代发展起来），比碱金属（Rb等）需要更多的激光波长- Sr光晶格时钟高达6个波长。然而，可靠的激光器（来自MSL）的可用性将使在短期内（5年内）在产品中使用Sr成为可能。据报道，已经有人尝试使用类似于Rb的方法来制造更紧凑的冷Sr源，但由于提案中解释的原因，另一种方法更可行。我们的方法结合了塞曼减速的长磁铁和真空镜的紧凑性（就像我们的金字塔设计一样）。在进一步的步骤中，我们可以将其发展成脉冲源，允许快速加载大量原子（例如在0.01秒内），但在测量期间（例如某些时钟的1秒）原子通量大大减少。这种带有脉冲阀的操作模式保存了原子，因此烘箱不需要频繁的重新装填，这对于现场部署的干涉仪来说尤其不方便。牛津大学的团队没有使用Sr（尽管PI过去使用过），但可以使用专业知识来构建新颖的设计（具有我们可以申请专利的功能，就像Rb的工作一样）。最佳结果将为msl生产的产品提供竞争优势。许可或其他事宜将由牛津大学创新有限公司（如Rb的冷原子来源）管理，以保护该技术并确保其仍然是英国工业的一部分。

We shall develop compact cold-atom sources for the alkali metals rubidium, caesium and potassium; and for the alkaline-earth metal strontium (Sr). These are very suitable for a range of applications in quantum technology and a components in the construction of apparatus for scientific research more broadly. Magneto-optical traps (MOTs) can capture slow atoms directly from an atomic vapour at room temperature to provide a very convenient source of cold atoms. We have used an arrangement of four triangular mirrors arranged as a pyramid inside the vacuum region to make a MOT in three separate experiments over the years. Recently we developed an improved design that is more compact and adjustable than other sources. A patent application covering the innovative features of this pyramid-MOT was applied for in April 2016 and we are constructing a prototype working with rubidium (Rb). We will develop this into a commercial product integrated with a laser system produced by M Squared Lasers (MSL). The company's titanium-doped sapphire lasers provide a high power, relative to other tuneable lasers, and unmatched stability. We shall make full use of the available laser power by tailoring the size of the mirrors and enclosing vacuum chamber to produce a high flux of atoms. This will a give strong signals and high repetition rate of measurements in instruments such as atomic interferometers which as the basis of the quantum technology used in gravimeters, gyroscopes etc. This device can laser cool the other alkali metal atoms Cs and K, and light at all the wavelengths required is available from MSL. Compact and reliable cold-atom sources are of themselves a useful device that can be sold in the scientific equipment market that constitutes much of MSL's present sales. While working on compact cold-atom sources we have noted the rapidly increasing interest in using cold strontium atoms for optical-lattice clocks, matter-wave interferometers and experiments with ultracold quantum gases. Strontium has intrinsic advantages such as rapid laser cooling, insensitivity to external magnetic fields and, for some isotopes, inter-atomic collisions are almost negligible. However working with cold Sr atoms much more technically demanding than Rb. In the traditional approach to laser cooling this species Sr atoms pass along the axis of a tapered solenoid (so-called Zeeman slowing developed in the 1980s) and many more laser wavelengths are required than for an alkali metals (Rb etc.) - up to 6 wavelengths for a Sr optical-lattice clock. However the availability of reliable lasers (from MSL) will make it possible to use Sr in products in the short term (within 5 years). Reportedly there have been attempts to make more compact sources of cold Sr using approaches similar to those for Rb but, for reasons explained in the proposal, a different method is more feasible. Our approach combines aspect of Zeeman slowing with long magnets with the compactness of in-vacuum mirrors (as in our pyramid design). In a further step we can develop this into a pulsed source that allows rapid loading of a high number of atoms (e.g. in 0.01 s) but with a much reduced flux of atoms during the measurement period (e.g. 1 s for some clocks). This mode of operation, with a pulsed valve, conserves atoms so that the oven does not need frequent reloading which is inconvenient especially for a field-deployed interferometer. The team in Oxford are not using Sr (although the PI has in the past) but the expertise is available to build the novel design (with features that we can patent, as in the work on Rb). The optimum outcome would provide a competitive edge for a product manufactured by MSLs. Licensing, or other, will be managed through Oxford University Innovation Ltd (as for the cold-atom source of Rb) to protect the technology and ensure that it remains part of a UK-based industry.