Development of Technologies for Sub-Quantum-Noise-Limited Gravitational-wave Interferometers

亚量子噪声限制引力波干涉仪技术发展

• 批准号: 0457264
• 负责人: Nergis Mavalvala
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0457264&HistoricalAwards=false
• 关键词: Development; Technologies; Sub; Quantum; Noise

Gravitational-wave interferometers measure optical signals generated by motion of the interferometer mirrors due to a passing gravitational wave (GW). Since the GW-induced motion is extremely small, quantum mechanical noise on the laser light can pose a serious limitation to the detector sensitivity. This quantum noise arises from two effects: (i) uncertainty in the number of photons at the interferometer output due to quantum mechanical fluctuations (known as shot noise); and (ii) light pressure which exerts forces that move the mirrors of the interferometer (known as radiation pressure noise or back action noise). The Heisenberg Uncertainty Principle sets a minimum for the product of the shot noise and back action noise, but it also allows the minimum shot noise to be lowered below the standard level, provided the back action noise is increased, or vice versa. This process is sometimes called "squeezing" because the noise from one process is "squeezed" into the other. For example, previous experiments have shown how laser light can be squeezed by making its amplitude fluctuations small, but giving greater uncertainty in its phase.Experiments will be carried out to generate and study squeezed states of light that are suitable for injection into a gravitational-wave interferometer. The effort will concentrate on the aspects of squeezed light most important for improving the sensitivity of future GW interferometers: vacuum squeezing at lower frequencies than have previously been explored. Two methods are being developed in parallel: (i) use of nonlinear optical media, such as crystals of lithium niobate, wherethe output light is squeezed due to correlations created by interaction of light beams in the crystal; and (ii) use of the coupling between the motion of a low-mass mechanical oscillator and intense laser light, which causes the light to be squeezed because the motion of the oscillator induced by forces due to amplitude fluctuations of the light couples to the phase of the light. The goal with both these experiments is to yield up to 6 dB of vacuum squeezing at a few hundred Hertz. In addition to improved sensitivity for gravitational wave detectors, the long-term technical advances necessary to achieve this goal will have applications in quantum optics, quantum information, (sub-)nanoscale mechanical systems and precision measurement.

重力波干涉仪测量由于传递引力波（GW）而通过干涉仪镜的运动产生的光信号。由于GW诱导的运动非常小，激光光上的量子机械噪声会严重限制检测器灵敏度。该量子噪声来自两个效果：（i）由于量子机械波动（称为射击噪声），干涉仪输出处光子数量的不确定性； （ii）施加的光压力会施加动作干涉仪的镜子的力（称为辐射压力噪声或背部动作噪声）。海森伯格的不确定性原理为射击噪声和背部动作噪声的乘积设置了最低限度，但也允许最小射击噪声降低到标准水平以下，只要增加了反作用噪声，反之亦然。这个过程有时被称为“挤压”，因为一个过程中的噪声被“挤压”到另一个过程中。例如，以前的实验表明，如何通过使其振幅波动较小来挤压激光光，但在其相时给出了更大的不确定性。将进行实例，以产生和研究适合在重力波动中注射的光的挤压状态。这项工作将集中在挤压光的各个方面，对于提高未来GW干涉仪的灵敏度最重要：在频率较低的频率下进行真空挤压比以前探索的频率较低。并行开发了两种方法：（i）使用非线性光学培养基，例如尼贝特锂的晶体，由于晶体中的光束相互作用而产生的相关性，因此挤压了输出光； （ii）在低质量机械振荡器的运动和强烈的激光之间使用耦合，这会导致光被挤压，这是因为由于光伴侣的振幅波动引起的力引起的振荡器的运动引起的振荡器的运动，从而导致光伴侣的运动。这两个实验的目标是在几百个赫兹挤出多达6 dB的真空吸尘器。除了提高对重力波探测器的敏感性外，实现此目标所需的长期技术进步​​还将在量子光学，量子信息，（子）纳米级机械系统和精度测量中应用。