Engineering a new generation of atom interferometers

设计新一代原子干涉仪

• 批准号: EP/R021236/1
• 负责人: Vera Guarrera
• 金额: $ 11.67万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FR021236%2F1
• 关键词: Engineering; new; generation; atom; interferometers

The huge progress achieved in the manipulation of quantum systems is opening novel routes towards the generation of realistic quantum-based technology. Notably many counterintuitive manifestations of quantum mechanics are turning to be key features for next generation devices, whose performances will beat those of classical machines. Atom interferometry is a hallmark example of that. According to quantum mechanics particles can behave like waves, showing interference as well as light does. In addition, they are very sensitive to the surrounding environment and they have mass, which make of them extremely powerful sensors for measuring linear accelerations and rotations. Implementing reliable atom interferometers for practical applications is however still challenging. State-of-the-art devices are based on atomic samples which are manipulated while they fall due to gravity inside a vacuum apparatus. These interferometers are currently reaching their ultimate performances being limited by technical issues. Their ultimate sensitivity depends in turn on the time available for the interrogation and on the finite atom number. An immediate solution to improve the sensitivity consists in enlarging the interrogation area, at the expenses of the size of the device, and increasing the atom number, at the expenses of the spatial resolution of the atomic probe. To obtain high sensitivity while maintaining the devices compact, a new generation of interferometers based on trapped and guided atoms is emerging. These devices have several advantages: the atoms do not fall and the interrogation time can be long, the use of BECs guarantees micrometrical spatial resolution, and interatomic interactions allow for the preparation of entangled states surpassing the standard quantum limit set by the finite atom number. New challenges also arise: the effects of the confining potentials and interatomic interactions must be controlled at a metrological level. The proposed project aims at realizing novel BEC-based quantum sensors which will be able to surpass the limitations of current trapped and guided interferometers by combining some of the most powerful manipulation techniques currently available in the field of ultracold atoms (and beyond). The two key elements are the accurate tailoring of the optical potentials by a spatial light modulator, and the control of the interactions. This exceptional experimental control will be assisted by theoretical optimization such as short-cut-to-adiabaticity and optimal control techniques. In most atom interferometers to date, the beam splitters are realized by pulsing two laser beams in Bragg or Raman configuration. We will instead engineer innovative splitters directly integrated into the optical waveguides which confine the atoms. They can operate continuously and without the need of extra laser beams. All the elements of the interferometer (beam splitter, phase accumulation and recombiner) will be integrated into the same device by properly sculpturing one single laser beam. First, a complete Mach-Zehnder operation will be performed with a condensate with tunable interactions. A negligible or weakly attractive value of the interactions will be used to suppress interaction-induced decoherence or create dispersionless wavepackets. As a result, high sensitivities are expected for such interferometer. In a second phase of the project, we will demonstrate a Sagnac-like interferometer with non-interacting condensates propagating in a close circuit. This will realize a guided atom gyroscope whose achievement has been a long-standing goal, and which finds an important application in inertial navigation. Finally, we will generate mesoscopic optical tweezers for realizing a dynamical double-well potential for Mach-Zehnder interferometry. By moving the tweezers apart we will control the coupling between the two wells, and by setting strong repulsive interactions we will produce optimally spin-squeezed states.

在操纵量子系统方面取得的巨大进步正在为基于量子的现实技术的产生开辟新的途径。值得注意的是，量子力学的许多违反直觉的表现正在成为下一代设备的关键特征，其性能将超过经典机器。原子干涉计量学就是一个标志性的例子。根据量子力学，粒子的行为可以像波一样，表现出像光一样的干涉。此外，它们对周围环境非常敏感，而且它们有质量，这使得它们成为测量直线加速和旋转的非常强大的传感器。然而，在实际应用中实现可靠的原子干涉仪仍然具有挑战性。最先进的设备是基于原子样品，当原子样品因真空装置内的重力而下落时，这些样品会被操纵。受技术问题的限制，这些干涉仪目前正在达到它们的最终性能。它们的最终灵敏度又取决于可用于询问的时间和有限原子数。提高灵敏度的一个直接解决办法是以牺牲装置的尺寸为代价来扩大询问区域，以牺牲原子探测器的空间分辨率为代价来增加原子数目。为了在保持器件紧凑的同时获得高灵敏度，基于捕获和引导原子的新一代干涉仪正在出现。这些器件有几个优点：原子不会坠落，询问时间可以很长，BEC的使用保证了微米级的空间分辨率，原子间的相互作用允许制备超过有限原子数设置的标准量子极限的纠缠态。还出现了新的挑战：必须在计量水平上控制限制势和原子间相互作用的影响。该项目旨在实现新型的基于BEC的量子传感器，通过结合目前在超冷原子领域(甚至更远的领域)可用的一些最强大的操纵技术，能够超越当前捕获和引导干涉仪的限制。两个关键要素是空间光调制器对光势的精确剪裁和相互作用的控制。这种特殊的实验控制将得到理论优化的辅助，如最短绝热和最优控制技术。迄今为止，在大多数原子干涉仪中，分束器是通过脉冲两束布拉格或拉曼配置的激光来实现的。相反，我们将设计创新的分路器，直接集成到限制原子的光波导中。它们可以连续运行，不需要额外的激光束。通过适当雕刻一束激光，干涉仪的所有元件(分束器、相位累加器和重组器)将集成到同一装置中。首先，完整的马赫-曾德尔运算将与具有可调相互作用的凝聚体一起执行。可以忽略的或弱吸引力的相互作用将被用来抑制相互作用引起的退相干或产生无色散的波包。因此，这种干涉仪具有很高的灵敏度。在项目的第二阶段，我们将演示一种类似Sagnac的干涉仪，该干涉仪具有非相互作用的凝聚体在闭合电路中传播。这将实现制导原子陀螺仪，它的实现是一个长期的目标，并在惯性导航中找到了重要的应用。最后，我们将产生介观光学镊子来实现马赫-曾德尔干涉术的动态双势垒。通过将镊子分开，我们将控制两个势垒之间的耦合，通过设置强烈的排斥相互作用，我们将产生最佳的自旋压缩状态。

项目成果

Generation of optical potentials for ultracold atoms using a superluminescent diode

使用超发光二极管产生超冷原子的光势

• DOI: 10.1103/physrevresearch.3.033241
• 发表时间: 2021
• 期刊: Physical Review Research
• 影响因子: 4.2
• 作者: Smith A

Bloch oscillations along a synthetic dimension of atomic trap states

• DOI: 10.1103/physrevresearch.5.033001
• 发表时间: 2021-12
• 期刊: Physical Review Research
• 影响因子: 4.2
• 作者: Christopher Oliver;Aaron Smith;Thomas Easton;G. Salerno;V. Guarrera;N. Goldman;G. Barontini;H. Price