Development of Quantum-Non-Demolition laser interferometer using displacement noise cancelling technique.

采用无位移噪声干涉仪技术，研制了突破标准量子极限的高灵敏度位移传感器。在提取原型DFI的思想和结果的基础上，展示了一套观察和克服SQL所需的基本技术。在对仪器进行了真空外壳、强光源等一系列升级后，我们尝试提高仪器作为位移传感器的灵敏度。Mach-Zhender干涉仪采用将光学元件刚性固定在单个基板上的单片干涉仪，其灵敏度受射散噪声（量子噪声）的限制降至几Hz，这相当于灵敏度仅为SQL的10倍的水平。

High-sensitivity displacement sensor had been developed to beat Standard Quantum Limit (SQL) using a technique of Displacement-noise Free Interferometer (DFI). Extracting the idea and results of prototype DFI, a package of basic techniques needed to observe and then overcome the SQL was demonstrated. After a series of upgrades of instruments including vacuum enclosure and intensive light source, we have tried to improve the sensitivity of the instrument as a displacement sensor. Employing the monolithic interferometer that fix the optics rigidly on the single base plate for a Mach-Zhender interferometer, the sensitivity of the interferometer was limited by the shot noise (quantum noise) down to several Hz, which corresponds to the level less sensitive by only factor of 10 to reach to the SQL.