论文标题
基于膜的光力加速度测定法
Membrane-based Optomechanical Accelerometry
论文作者
论文摘要
光力学加速度计有望量子限制的读数，高检测带宽，自校准和辐射压力稳定。我们提出了一个简单，可扩展的平台，该平台以声音频率的纳米$ g $敏感性实现了这些好处，该平台基于一对垂直集成的Si $ _3 $ n $ _4 $ _4 $ _4 $膜具有不同刚度，形成了光腔。作为演示，我们集成了超高Q（$> 10^7 $），毫米级SI $ _3 $ n $ _4 $ _4 $ trampoline膜上，上面是同一Si芯片上未完美的膜，形成了finesse $ \ natercal $ \ nathcal {f} \ and cavity。使用传输中的直接照相检测，我们通过以7 fm/$ \ sqrt {\ text {hz}} $的射击量不重点解决膜的相对位移，得出了562 N $ g/\ sqrt a的热 - 净加速度的敏感性，产生了热量限制的加速度。集中在基本的蹦床共振（40 kHz）上。为了说明辐射压力稳定的优势，我们将蹦床浸泡到4 Mk的有效温度，并利用减少的能量方差来解决50 n $ g/\ sqrt {\ sqrt {\ text {hz}} $的应用随机加速度，并在几分钟内进行。将来，我们设想了在低温恒温器中运行的这些设备的小型阵列，以寻找基本的弱力，例如暗物质。
Optomechanical accelerometers promise quantum-limited readout, high detection bandwidth, self-calibration, and radiation pressure stabilization. We present a simple, scalable platform that enables these benefits with nano-$g$ sensitivity at acoustic frequencies, based on a pair of vertically integrated Si$_3$N$_4$ membranes with different stiffnesses, forming an optical cavity. As a demonstration, we integrate an ultrahigh-Q ($>10^7$), millimeter-scale Si$_3$N$_4$ trampoline membrane above an unpatterned membrane on the same Si chip, forming a finesse $\mathcal{F}\approx2$ cavity. Using direct photodetection in transmission, we resolve the relative displacement of the membranes with a shot-noise-limited imprecision of 7 fm/$\sqrt{\text{Hz}}$, yielding a thermal-noise-limited acceleration sensitivity of 562 n$g/\sqrt{\text{Hz}}$ over a 1 kHz bandwidth centered on the fundamental trampoline resonance (40 kHz). To illustrate the advantage of radiation pressure stabilization, we cold damp the trampoline to an effective temperature of 4 mK and leverage the reduced energy variance to resolve an applied stochastic acceleration of 50 n$g/\sqrt{\text{Hz}}$ in an integration time of minutes. In the future, we envision a small-scale array of these devices operating in a cryostat to search for fundamental weak forces such as dark matter.
