Suppressing Rayleigh Scatter in Levitated Optomechanics

悬浮光力学使用一个纳米粒子作为精确测量的平台，将其置于激光聚焦处的真空中。目前，国际上的努力在于试图利用这些系统和相关系统达到量子状态，以便将其用作弱外部扰动（如引力场）的传感器。悬浮纳米粒子是一条很有前途的途径，它将远远超过目前现有技术的灵敏度。然而，这些先进的传感应用需要创建纳米粒子的大空间叠加，这受到快速退相干的影响。特别是，悬浮粒子受到激光本身的退相干；粒子散射的激光光子随机地扰乱了它的运动。该项目的主要目的是证明抑制瑞利散射光作为悬浮光力学中退相干的关键来源。为此，我将设计并构建一个实验，利用半球面镜通过相消干涉抑制瑞利散射。我也可能会探索这个系统在高级传感和更基本的问题上的潜在应用，比如量子力学定律如何在宏观尺度上运作。

Levitated Optomechanics uses a single nanoparticle, held in vacuum at the focus of a laser, as a platform for precision measurement. International effort now lies in attempting to reach the quantum regime using these and related systems in order to be utilised as sensors of weak external perturbations such as the gravitational field. Levitated nanoparticles are a promising route towards far exceeding the sensitivities of currently existing technologies. However, these advanced sensing applications require the creation of large spatial superpositions of the nanoparticle, which suffers from rapid decoherence. In particular, levitated particles are subject to decoherence from the laser itself; the laser photons which the particle scatters, randomly perturb its motion. The main objective of the project is to demonstrate the suppression Rayleigh scattered light as a key source of decoherence in levitated optomechanics. To do this, I will aim to design and construct an experiment which will utilise a hemispherical mirror to suppress Rayleigh scatter by destructive interference. I may also explore the potential applications of the system to advanced sensing and more fundamental questions regarding how the laws of quantum mechanics operate on the macroscopic scale.