Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, 02139, USA.
Quantum Information Processing group, Raytheon BBN Technologies, 10 Moulton Street, Cambridge, MA, 02138, USA.
Nat Commun. 2019 Mar 6;10(1):1070. doi: 10.1038/s41467-019-08948-x.
Despite linear-optical fusion (Bell measurement) being probabilistic, photonic cluster states for universal quantum computation can be prepared without feed-forward by fusing small n-photon entangled clusters, if the success probability of each fusion attempt is above a threshold, [Formula: see text]. We prove a general bound [Formula: see text], and develop a conceptual method to construct long-range-connected clusters where [Formula: see text] becomes the bond percolation threshold of a logical graph. This mapping lets us find constructions that require lower fusion success probabilities than currently known, and settle a heretofore open question by showing that a universal cluster state can be created by fusing 3-photon clusters over a 2D lattice with a fusion success probability that is achievable with linear optics and single photons, making this attractive for integrated-photonic realizations.
尽管线性光学融合（贝尔测量）是概率性的，但如果每次融合尝试的成功率高于某个阈值，[公式：见正文]，那么通过融合小的 n 光子纠缠簇，可以在没有前馈的情况下制备用于通用量子计算的光子簇态。我们证明了一个通用的边界[公式：见正文]，并开发了一种概念方法来构建长程连接的簇，其中[公式：见正文]成为逻辑图的键渗流阈值。这种映射让我们找到了所需融合成功率低于现有技术的构建方法，并通过证明通过融合具有线性光学和单光子可实现的融合成功率的 2D 格点上的 3 光子簇，可以创建通用的簇态，从而解决了一个长期存在的开放性问题，这使得这种方法在集成光子学实现方面具有吸引力。
