Superfluid Optomechanics

在过去的几年里，光学力学领域取得了迅速的发展，从光学和机械系统之间耦合的原理证明到在少数这些设备中观察量子效应。在同一时期，光学机械系统和其他AMO系统（如超冷原子和金刚石NV中心）之间的连接已经成为控制混合系统中量子信息的有前途的途径。在这个项目中，我们正在努力通过实现一种新型的光学机械系统来扩展这两方面的努力，这种光学机械系统能够达到量子机制，同时还能够容纳与光学腔强耦合的冷分子。我们正在建造的设备也将比现有的光学机械设备更加坚固和紧凑。为了实现这些目标，我们正在使用充满超流氦的高精细光学腔。所述空腔形成在一对光纤之间。精密加工的玻璃套圈被用来排列光纤和容纳超流体。机械元素将是填充在两个纤维之间的超流氦的振动模式。这种设计消除了所有的机械对准，并且应该导致非常稳定的设备。 数值估计表明，该设备将提供一系列量子现象，包括超流体模式的零点运动的观测，压缩光的产生，以及光学位移测量的量子反作用的测量。此外，我们还在探索超流-真空界面的光学力学性质，方法是仅用超流填充部分腔。超流氦可以作为各种类原子系统（如亚稳态氦二聚体分子和电子泡）的宿主，这些系统可以与氦中的光学腔和声波相互作用。将光学机械学与这种原子状系统相结合，将大大提高这些设备的多功能性。 我们正在使用这些超流体光学机械设备来研究测量的量子极限，并产生超稳定的光，用于在量子极限灵敏度下工作的仪器。 这项工作也为激光光学、低温学、低噪声测量、信号处理、数据分析和量子光学方面的研究生提供了有价值的培训。这种培训将使他们能够在各种各样的环境中进行基础和应用研究。

The field of optomechanics has progressed rapidly in the past few years from proof-of-principle demonstrations of coupling between optical and mechanical systems to the observation of quantum effects in a handful of these devices. During the same period, connections between optomechanical systems and other AMO systems such as ultracold atoms and diamond NV centers have emerged as promising routes towards controlling quantum information in hybrid systems. In this project, we are working to extend both of these efforts by realizing a new type of optomechanical system capable of reaching the quantum regime while also playing host to cold molecules strongly coupled to an optical cavity. The devices we are building will also be substantially more robust and compact than existing optomechanical devices.To achieve these goals, we are using high finesse optical cavities filled with superfluid helium. The cavities are formed between a pair of optical fibers. Precision-machined glass ferrules are being used to align the fibers and to contain the superfluid. The mechanical element will be the vibrational modes of the superfluid helium filling the space between the two fibers. This design eliminates all mechanical alignments, and should result in a very stable device. Numerical estimates suggest that this device will provide access to a range of quantum phenomena, including observations of the zero-point motion of the superfluid modes, the generation of squeezed light, and measurements of the quantum back action of an optical displacement measurement. In addition, we are exploring the optomechanical properties of superfluid-vacuum interfaces by filling the cavity only partially with superfluid.Superfluid helium can play host to a variety of atom-like systems (such as metastable helium dimer moledules and electron bubbles) that can interact with both the optical cavity and the sound waves in the helium. Combining optomechanics with such atom-like systems would greatly enhance the versatility of these devices. We are using these superfluid optomechanical devices to study the quantum limits of measurements, and to produce ultrastable light for use in instruments operating at the quantum limit of sensitivity. This work is also providing valuable training for graduate students in laser optics, cryogenics, low-noise measurements, signal processing, data analysis, and quantum optics. This training will allow them to pursue basic and applied research in a wide variety of settings.