Fiber Mirror Facility Upgrade for Quantum Optics and Sensing

光腔极大地增强了光与物质的相互作用，使其成为光学、量子光学和传感中无处不在的工具。最近，出现了微小的“光纤腔”，提供了显著更高的带宽和更严格的限制，从而进一步促进了这些相互作用。因此，我们现在六个核心研究方向中有五个依赖于光纤腔技术。所需的光纤镜片基板是在麦吉尔的一个共享设施中激光加工的，虽然这一系统使我们的研究跃升到几个领域的前沿，但它的低公差和缺乏灵活性现在威胁着进一步的进展。因此，我们要求进行升级，以提高精度、设计灵活性和吞吐量。每个研究领域都将从这一点上受益匪浅，但最近的两项突破尤其提供了非同寻常的机遇，促使其立即升级。首先，在光力学领域，我们成功地实现了一个由光纤腔内的超低噪声蹦床微机械传感器组成的系统，该传感器的运动将受到前所未有的频带内量子辐射压力涨落的影响。这种以量子为主导的体制预示着“压缩”光的产生，这种“压缩”光可用于超越“标准量子极限”，并通过反馈准备任意的运动量子态，从而实现量子崩塌的基本测试(例如，由于重力)，以及用于暗物质搜索和力显微镜的量子增强型传感器。然而，这些令人兴奋的机会需要显著改进的光纤反射镜来有效地耦合量子光：我们需要精确定位、超光滑和接近平坦的表面，而这是我们目前无法制造的。第二，在辐射剂量学领域，我们最近申请了一项以水为活性介质的组织等效在体光纤腔剂量计的专利。我们与Enger教授(MUHC)的合作现在已经在自由空间水中观测到了有希望的信号，验证了我们镜面涂层的辐射硬度，并开发了实现最佳剂量计的技术和详细的理论。我们知道，目标灵敏度需要比我们现有设备中可能的曲率半径大得多的反射镜。拟议的升级--显然利用了几乎所有现有的基础设施--解决了所有上述问题，同时提高了可靠性和吞吐量。它包括用于多次烧蚀多个光纤尖端上的任意轮廓并在烧蚀过程中和之后自动仿形的电动工作台、具有行业领先的角度公差以消除有害的不对准的光纤劈刀，以及所有必要的集成硬件。除此之外，我们的设施还为哈佛大学、丹麦理工大学、韩国大学和艾伯塔省的研究人员提供光纤。这里要求的基础设施将提高生产效率、灵活性和可靠性，从而使该社区得以扩展。

Optical cavities vastly enhance light-matter interactions, making them a ubiquitous tool in optics, quantum optics, and sensing. Recently, microscopic "fiber cavities" have emerged, offering significantly higher bandwidth and tighter confinement, thereby boosting these interactions even further. As a result, five of our six core research directions now rely on fiber cavity technology. The requisite fiber mirror substrates are laser-machined in a shared facility at McGill, and, while this system has vaulted our research to the leading edge of several fields, its low tolerances and lack of flexibility now threaten to halt further progress. As such, we request an upgrade that will improve precision, design flexibility, and throughput. Each research area will greatly benefit from this, but two recent breakthroughs in particular present extraordinary opportunities that prompt an immediate upgrade. First, in the field of optomechanics, we have successfully realized a system comprising an ultralow-noise "trampoline" micromechanical sensor within a fiber cavity, whose motion will be dominated by quantum radiation pressure fluctuations over an unprecedented band of frequencies. This quantum-dominated regime heralds the generation of "squeezed" light useful for surpassing the "standard quantum limit" and preparing arbitrary motional quantum states via feedback, enabling fundamental tests of quantum collapse (e.g. due to gravity), and quantum-enhanced sensors for dark matter searches and force microscopy. However, these exciting opportunities require significantly improved fiber mirrors to efficiently out-couple quantum light: we need precisely positioned, ultrasmooth, and near-flat surfaces that we cannot currently fabricate. Second, in the field of radiation dosimetry, we recently patented a tissue-equivalent in vivo fiber-cavity dosimeter with water as the active medium. Our collaboration with Prof. Enger (MUHC) has now observed promising signals in free space water, verified the radiation hardness of our mirror coatings, and developed techniques and a detailed theory for realizing the optimal dosimeter. We know that the targeted sensitivities require mirrors with much larger radius of curvature than is possible in our existing facility. The proposed upgrade -- which notably utilizes almost all of the existing infrastructure -- addresses all of the above issues, while increasing reliability and throughput. It includes motorized stages for multi-shot ablation of arbitrary profiles on multiple fiber tips and automatic profiling during and after ablation, a fiber cleaver with industry-leading angular tolerances to eliminate detrimental misalignment, and all necessary integration hardware. Beyond this, our facility provides fibers to researchers at Harvard, TU Denmark, Korea University, and Alberta. The infrastructure requested here will increase production, flexibility, and reliability, allowing this community to expand.