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多粒子纠缠态(如W态)在量子计算、真随机数产生等方面有着广泛的应用空间,因此受到越来越多的关注.其中W态纠缠还具有显著的抗退相干性.本文提出一种用于产生高阶单光子W态的通用实验装置,这种装置基于由激光直写制备的三维集成光子波导结构.此外,由于在量子光学中,通常需要精确表征量子元件的幺正矩阵,本文提出一种新颖的方法,即使用传统的光干涉测量法实现这种表征.对于幺正矩阵元,分别使用强度测量和基于利萨如图形的高灵敏度相位测量获得其模和幅角.在这种方法中,相位测量的复杂程度与通道数量呈线性关系,因而也适用于表征通道更多的量子元件.实验表明,该方法可以高精度地表征W态制备装置中量子门的保真度.
Multipartite entangled states (such as W states) have a wide range of applications in quantum computing and true random number generation and are therefore attracting more and more attentions, and W entanglement also has significant anti-decoherence.This paper presents a A universal experimental setup for generating high-order single-photon W states based on a three-dimensional integrated photonic waveguide structure fabricated by laser direct writing.Furthermore, since in quantum optics it is often necessary to accurately characterize the unitary matrix of quantum elements, In this paper, a novel method is proposed, which uses traditional optical interferometry to achieve this characterization. For the unitary matrix elements, the modes and angles are obtained respectively using intensity measurements and high-sensitivity phase measurements based on Lissajous figures. In In this method, the complexity of phase measurement is linear with the number of channels, and thus it is also suitable for characterizing more quantum elements in channels.Experiments show that this method can characterize the fidelity of quantum gates in W-state devices with high accuracy .