基于低频相位测量的量子光纤干涉仪

By utilizing quantum resources, in particular non-classical probe states, quantum metrology can go beyond the limit of classical metrology schemes. Therefore quantum metrology may find important applications in searching ultra-weak signals, such as gravitational wave detection. However, such technique shares the same drawback with other quantum technologies: its performance is very sensitive to experimental imperfections, for example particle loss, dephasing noise, etc. It is the major challenge for the applications of quantum metrology in practical systems. Fiber interferometers can be used to detect displacement, strain, magnetic field, rotation and so on. Due to having advantages such as high sensitivity, wide band, EMI immunity, electrically passive, fiber interferometers are widely applied in measurement and sensing. In this project, we will enhance the precision of a fiber interferometer by introducing the techniques in quantum precision measurement. Meanwhile, we will investigate the applications of utilizing the high-frequency sidebands of the squeezed light to measure low-frequency phase signals, and its tolerance and experimental imperfections. Our results will make important contributions to the development of quantum-enhanced measurement techniques in the real world.

量子精密测量（quantum metrology）通过使用量子资源特别是非经典探测态，可以突破传统精密测量方案的经典极限，因此对于极微弱信号的探测(如引力波探测)有着重要应用。然而与其他量子技术类似，量子精密测量对系统噪声极为敏感，如光子损耗、退相干噪声等，因而难以实际应用。光纤干涉仪可以用于位移、应变、磁场、转动等诸多物理量的测量，具有灵敏度高、频带宽、抗电磁干扰、电绝缘性等优点，在测量及传感领域有着广泛的应用。本项目中，我们将量子精密测量技术与光纤干涉仪相结合，设计并研制低损耗、低噪声的全光纤干涉仪，运用量子压缩光源提高相位测量精度。同时我们还将探究一种高频压缩光通过调制转移方法在低频段实现相位测量的方案，揭示其理论原理和适用范围。通过本项目的研究成果，我们能获取关于量子精密测量的新认识和新机理，进一步推动该技术向实用化迈进。

光学干涉相位测量是很多物理量精密测量的重要方法，利用量子光源提高干涉仪测量精度，已成为光学领域的重要研究方向。光纤具有体积小、易搬运、集成度高、抗电磁干扰等优势，使得高灵敏应变传感器、光纤陀螺仪等在传感测量领域得到广泛应用。本项目提出将量子测量与光纤传感结合起来实现超高精度光学测量。我们设计并研制了低损耗、低噪声的全光纤马赫曾德干涉仪，总损耗低至35%（包括空间光的耦合损耗），干涉效率达到99%。通过改进非简并光学参量放大腔的共振方式及相位锁定方法，在傅里叶频率2-5MHz处获得压缩度8dB以上的正交相位压缩光。提出一种调制转移技术解决了高频压缩光测量低频信号的难题，实验在30kHz-150kHz频率范围测试到超越经典散粒噪声2dB的相位精度提升。相比于传统直接搭建低频压缩光源，此方法可以有效利用当前相关光学技术，具有方法简单，低成本，效率高的特点。通过本项目的研究成果，我们能获取关于量子精密测量的新认识和新机理，进一步推动该技术向实用化迈进。