利用EPR纠缠光提高引力波探测的灵敏度

Gravitational wave detection, which is one of the most important research topics in the field of optical precision measurement, has significant applications in the fields of astronomy and cosmology. Due to the quantum nature of laser, the sensitivity of gravitational wave detection is limited by quantum noise. In order to reduce the quantum noise in the whole band, the frequency-dependent squeezed vacuum state should be injected into the dark port of the interferometer. The generation of the frequency-dependent squeezed vacuum state needs long base-line, low-loss filter cavity, so we plan to improve the sensitivity of gravitational wave detection via EPR entanglement. The signal beam is resonant in the interferometer. The idle beam, being far detuned from the interferometer, will experience frequency-dependent quadrature rotation. The output field of the interferometer is measured with a bichromatic local oscillator, so the measurement of a fixed quadrature of the out-going idle beam conditionally squeezes the input signal beam in a frequency-dependent way. This scheme achieve broadband squeezing of the total quantum noise via EPR entanglement. . In this project, we will study the main factors affecting the sensitivity of gravitational wave detection, the generation of EPR entangled states, the input and output characteristics of Michelson interferometers, and enhancing the sensitivity of gravitational wave detection via EPR entanglement.

引力波探测是光学精密测量领域的重要研究课题，在研究天文学，探索宇宙奥秘等领域具有极高的应用价值。由于激光量子性的存在，引力波探测的灵敏度受到了量子噪声的限制。为了在宽带范围内降低量子噪声，我们需要将依赖于频率的真空压缩态注入干涉仪的暗端。但依赖于频率的真空压缩态的制备需要引入大型的光学腔，因此我们计划利用EPR纠缠态提高引力波探测的灵敏度。通过控制纠缠态光场的信号光在干涉仪内共振，闲置光远失谐于干涉仪，使得闲置光经历依赖于频率的正交分量旋转。最后，用双色本振光测量干涉仪的输出场，则闲置光固定正交分量的量子噪声将条件性的压缩信号光的某一正交分量的量子噪声。. 本项目将详细研究影响引力波探测灵敏度的主要因素，高强度EPR纠缠态的制备，迈克尔逊干涉仪的输入输出特性，利用EPR纠缠态提高引力波探测的灵敏度。

引力波探测是光学精密测量领域的重要研究课题之一，在研究天文学，探索宇宙奥秘等领域具有极高的应用价值。2015年得首次直接探测引力波也开启了引力波天文学的新时代。作为地球上灵敏度最高的装置，大型双循环迈克尔逊激光干涉仪能够测量10^(-20) m/√Hz的臂长变化，相当于原子核半径的十万分之一。本项目在理论和实验证明了双循环迈克尔逊干涉仪的类电磁诱导透明现象，且通过改变干涉仪的臂长差，可以调节耦合强度，进而控制透明窗口的宽度；理论上计算了双循环迈克尔逊干涉仪对压缩真空态的调控，发现耦合强度可以控制压缩角的旋转频率。.纠缠态光场是量子信息科学的重要资源之一，在量子通信、量子计算和量子传感等领域有着广泛的应用。本项目利用两组份纠缠态光场实现了可连续操控的1→2量子态分发器，接收端的最高保真度为0.95；通过优化提取损耗与位相抖动，将相干态量子隐形传输的保真度提高至0.905；实现了连续变量1→3量子远程克隆，获得的两个克隆态保真度为0.64，反克隆态的保真度为0.49。