近日，美国斯坦福大学的Monika Schleier-Smith及其研究团队取得一项新进展。经过不懈努力，他们成功生成由光子介导纠缠工程化的原子系综图态。相关研究成果已于2024年3月1日在国际知名学术期刊《自然—物理学》上发表。

本文成功生成了原子自旋系综连续变量图态，这些状态构成了图的节点。研究人员通过结合光学腔中全局光子介导的相互作用和局部自旋旋转，对图边编码的纠缠结构进行了编程。通过调整两个子系统之间的纠缠，研究人员要么在每个子系统中定位相关性，要么实现Einstein–Podolsky–Rosen导引——一种强纠缠形式，可以通过对另一个子系统的测量从一个子系统提取精确的信息。

此外，他们进一步设计了一个四模方形图态，突出了该方法的灵活性。该方法可扩展到更大更复杂的图形，为基于测量的量子计算和量子计量中的高级协议奠定了基础。

据悉，图态是一大类纠缠量子态，每个纠缠量子态由表示子系统之间关联的边组成的图定义。这些态构成了量子计算和量子增强测量的通用资源。它们的生成和工程化需要对纠缠进行高水平的控制。

附：英文原文

Title: Graph states of atomic ensembles engineered by photon-mediated entanglement

Author: Cooper, Eric S., Kunkel, Philipp, Periwal, Avikar, Schleier-Smith, Monika

Issue&Volume: 2024-03-01

Abstract: Graph states are a broad family of entangled quantum states, each defined by a graph composed of edges representing the correlations between subsystems. Such states constitute versatile resources for quantum computation and quantum-enhanced measurement. Their generation and engineering require a high level of control over entanglement. Here we report on the generation of continuous-variable graph states of atomic spin ensembles, which form the nodes of the graph. We program the entanglement structure encoded in the graph edges by combining global photon-mediated interactions in an optical cavity with local spin rotations. By tuning the entanglement between two subsystems, we either localize correlations within each subsystem or enable Einstein–Podolsky–Rosen steering—a strong form of entanglement that enables the extraction of precise information from one subsystem through measurements on the other. We further engineer a four-mode square graph state, highlighting the flexibility of our approach. Our method is scalable to larger and more complex graphs, laying groundwork for measurement-based quantum computation and advanced protocols in quantum metrology.

DOI: 10.1038/s41567-024-02407-1

Source: https://www.nature.com/articles/s41567-024-02407-1