Collective motion of ultracold atoms strongly coupled to an optical resonator

众所周知，量子力学理论限制了我们可以收集到的关于某个物理系统的信息量。探索量子计量极限的一条途径是测量宏观机械振荡器的运动，例如纳米制造的悬臂或各种类型的膜。虽然这些系统还没有达到灵敏度和状态准备的量子极限，但它们有望解决量子力学是否在描述更大物体时保持其有效性这一有趣的问题。这个项目代表了微观力学和量子测量的一种新方法。其中，超冷原子宏观系综的集体运动取代了纳米制造的机械谐振器。使用该系统的优点是谐振腔可以直接冷却到其量子力学基态，并且谐振腔的驱动和测量机制坚实地建立在量子光学的基础上。在这项工作中，PI和他的学生将研究量子有限测量，双稳态运动的经典和量子方面，以及最终，机械物体的量子波动和单模光场之间强耦合的影响。这项工作将通过为接近量子有限性能提供明确的指导方针，为各种类型的量子技术的发展提供信息，包括超导量子干涉（SQUID）放大器和纳米机械谐振器。实现探测冷原子运动的量子极限也直接适用于目前正在开发和部署的基于冷原子的干涉测量传感器。最后，在培养量子光学、原子物理和凝聚态物理交叉领域的研究生时，该项目将有助于培养量子科学家和工程师，他们将认识到新生量子技术的好处。

The theory of quantum mechanics famously places restrictions on the amount of information we can ever gather about some physical system. One route for exploring the limits of quantum metrology is the measurement of motion of macroscopic mechanical oscillators, for example nanofabricated cantilevers or membranes of various types. While these systems have yet to reach quantum limits of sensitivity and state-preparation, they hold promise for addressing the intriguing question of whether quantum mechanics retains its validity for describing ever-larger objects. This project represents a novel approach to micro-mechanics and quantum measurement. In it the collective motion of a macroscopic ensemble of ultracold atoms takes the place of the nanofabricated mechanical resonator. The advantages of using this system are that the resonator can be cooled directly to its quantum-mechanical ground state and that the mechanisms for actuating and measuring the resonator are founded solidly on quantum optics. In this work, the PI and his students will investigate quantum limited measurements, classical and quantum aspects of bistable motion, and, ultimately, the effects of strong coupling between the quantum fluctuations of a mechanical object and a single-mode light field.This work will inform the development of quantum technologies of various types, including superconducting quantum-interference (SQUID) amplifiers and nanomechanical resonators, by giving clear guidelines for approaching quantum limited performance. Achieving quantum limits for detecting the motion of cold atoms is also directly applicable to cold-atom-based interferometric sensors that are being presently developed and deployed. Finally, in training graduate students at the intersection of quantum optics, atomic physics, and condensed-matter physics, the project will help to develop the quantum scientists and engineers who will realize the benefits of nascent quantum technologies.