Operational characterization of multi-photon entanglement in linear optics networks

2020年，我们继续对多光子线性光学网络中量子态的表征进行了研究，以实验可行的方式建立了多光子线性光学网络中互补性质的表征理论，并发表在《新物理杂志》2020年第22期(103054)上。然后，该理论可用于多光子LON系统的纠缠检测，而不会陷入玻色子采样的计算复杂性。它允许我们将多体量子体系中纠缠检测的成熟方法推广到多体离子。因此，多光子LON系统中的“模间纠缠”可以在测量中被物理探测到。我们已经在“AQIS 2020”和“QIP 2021”会议上公布了这一结果。除了纠缠检测之外，我们还想以很长的时间来评估量子态和目标态之间的相似性。为此，我们首先需要建立一种利用状态验证器进行量子态保真度估计的理论。因此，我们提出了一种基于局域测量的量子纠缠态的量子保真度计算方案，该方案已发表在《熵22,889(2020)》中。基于这一理论，人们可以在实验中构造和评估离子中多光子态的状态验证器，以估计量子态保真度的下界和上界。这一成果已在会议《量子信息科学研讨会2020》上发表。

In 2020, we have continued our research on the characterization of quantum states in multiphoton linear optics networks.We have established a theory for the characterization of complementary properties in multiphoton linear optics networks (LONs) in an experimentally feasible way, which has been published in “New Journal of Physics 22, 103054 (2020)”. This theory can be then employed for entanglement detection in multiphoton LON systems without falling into the computational complexity of boson sampling. It allows us to extend well-established methods for entanglement detection in multipartite qudit systems to multipartite LONs. As a result, “entanglement between modes” in multiphoton LON systems can be physically detected in measurements. We have presented this result at the conferences “AQIS 2020” and “QIP 2021”.A step further than the entanglement detection, we would like to evaluate the similarity between a quantum state and a target state in LONs. To this end, we need to first establish a theory for quantum state fidelity estimation employing state verifiers. We have therefore proposed a protocol for quantum state fidelity estimation for entangled states in bipartite qudit systems employing a set of local measurements, which has been published in “Entropy 22, 889 (2020)”. Based on this theory, one can construct and evaluate state verifiers for multiphoton states in LONs in experiments to estimate lower and upper bounds on quantum state fidelity. This result has been presented at the conference “Workshop on quantum information science 2020”.