超越标准量子极限的多参数联合测量

利用量子纠缠可使两个非对易物理量的测量精度同时超越标准量子极限(SQL)。本项目采用超冷原子和光学参量放大器两种典型物理系统，在制备连续变量原子玻色爱因斯坦凝聚体(BEC)和光场量子纠缠态的基础上，采用SU(1,1)非线性干涉仪，同时测量多个非对易物理量、且每个物理量的测量精度均超越SQL。项目的创新性如下: 1)在超越SQL的测量中，大多数研究集中在如何精确地测量单一物理量，本项目重点研究多个非对易物理量的测量，揭示如何在量子增强的联合测量中，优化量子资源的配置；2)以往在原子干涉仪中只测量一个参数，本项目拟利用BEC中的纠缠原子实现两个参数同时测量；3)多参数量子增强测量的研究目前尚无对实际样品进行测量的报道，本项目拟利用非线性光学干涉仪在实际样品的多参数检测中实现量子增强；4)本项目分别采用冷原子和光学参量放大器两种系统，为进一步研究如何在不同应用领域选择适当的物理系统提供依据。

Joint measurement of two non-commuting observable with precision higher than the standard quantum limit (SQL) can be realized by using Einstein-Podolsk-Rosen (EPR) states. We propose to generate continuous variable EPR states for precision measurement by using two kinds of physics systems. One is cold atoms, the other is optical parametric amplifiers. Then we study the quantum enhanced joint measurement by using SU(1,1) nonlinear interferometer in the two systems, respectively. The innovations of our proposal are the following. First, in the area of quantum enhanced precision measurement, most previous study is committed to improving the measurement precision of one parameter, whereas we focus on studying the joint measurement of non-commuting multi-parameters. We will investigate how to fully use the quantum resource to achieve the best quantum enhancement in the multi-parameters measurement. Second, we investigate the joint measurement of two non-commuting observable using the atomic interferometer, which has not been demonstrated yet. Third, all the quantum enhanced measurements using SU(1,1) interferometer formed by two optical parametric amplifiers are proof-in-principle demonstration, but we propose to show the quantum improvement in the joint measurement of a real sample. Fourth, we will investigate and compare the SU (1,1) interferometers which are based on the cold atomic system and optical system, respectively. The results will reveal the applicability of each physical system, which is benificial for further exploring its practical applications.