论文标题
相位灵敏度接近量子cramer-rao，以改良的SU（1,1）干涉仪结合
Phase sensitivity approaching quantum Cramer-Rao bound in a modified SU(1,1) interferometer
论文作者
论文摘要
SU（1,1）干涉仪基于非线性元素的使用，优于相位灵敏度中的被动干涉仪。但是，随着第二个非线性元素歼灭内部的一些光子，SU（1,1）干涉仪无法充分利用带有相信息的光子。在这里，我们专注于提高相位灵敏度，并基于修改后的SU（1,1）干涉仪提出了一种新协议，其中第二个非线性元件被束分配器代替。我们利用两个连贯的状态作为输入，并在输出处实施平衡的同源测量。我们的分析表明，我们提出的协议可以实现亚弹药限制的相位灵敏度，并且对光子丢失和背景噪声非常有力。我们的工作对于使用SU（1,1）干涉仪的实用量子计量仪很重要。
SU(1,1) interferometers, based on the usage of nonlinear elements, are superior to passive interferometers in phase sensitivity. However, the SU(1,1) interferometer cannot make full use of photons carrying phase information as the second nonlinear element annihilates some of the photons inside. Here, we focus on improving phase sensitivity and propose a new protocol based on a modified SU(1,1) interferometer, where the second nonlinear element is replaced by a beam splitter. We utilize two coherent states as inputs and implement balanced homodyne measurement at the output. Our analysis suggests that the protocol we propose can achieve sub-shot-noise-limited phase sensitivity and is robust against photon loss and background noise. Our work is important for practical quantum metrology using SU(1,1) interferometers.
