三维时间片最大纠缠态的最优检测

Optimized detection of maximally entangled time-bin qutrits

如何实现高维纠缠态的纠缠检测是量子科技理论和实验研究的一项重要内容。传统的基于保真度的纠缠见证并不能适用于检测所有种类的纠缠态,且其测量组合的数目也并非最优。通过在光子的时间片自由度上制备出两体三维最大纠缠态,在使用传统纠缠见证无法认定其纠缠性质的情况下,采用基于凸优化理论的纠缠检测方法对该量子态的纠缠维度进行检测。结果表明,凭借新方法可获得更有效的测量方案,能够高效准确地认证目标态的纠缠维度,并将传统纠缠见证实验所需的15组测量组合减少至6组。

The detection of high-dimensional entanglement is an important challenge in both theoretical and experimental aspects of quantum information science and technology.The traditional entanglement witness based on fidelity is not suitable for detecting all kinds of entanglement states,and the number of measurement combinations is not optimal.A new algorithm based on convex optimization theory has been proposed to remedy the situation.The performance of both approaches on a bipartite time-bin-entangled qutrit is experimentally test.When the traditional entanglement witness cannot determine its entanglement property unambiguously,it’s switched to the optimization-based method.The results show that a simpler and more effective measurement scheme can be obtained by using the new method,which can efficiently and accurately verify the entanglement dimension of the target qutrit.In addition,compared with the traditional entanglement witness,the new method only requires counting 6 different pairs of coincidences instead of 15.