近日，美国加州理工学院的Oskar Painter及其研究团队取得一项新进展。经过不懈努力，他们利用单量子发射体确定性地生成多维光子团簇态。相关研究成果已于2024年2月28日在国际知名学术期刊《自然—物理学》上发表。

该研究团队提出并实验验证了一种在微波领域实现高效资源利用的方案，用于确定性地生成二维光子团簇态。研究人员巧妙地利用耦合谐振器阵列作为慢光波导，同时引入单个可调谐的传输子量子比特作为量子发射体，并结合第二个辅助传输子作为可切换的镜像。

这种设计使得纠缠光子波包能够实现快速、成型的发射，并且能够实现对发射体量子比特的选择性延时反馈。通过这些技术手段，研究人员成功地以70%的保真度生成了包含四个光子的二维团簇态，并通过量子态层析重建技术进行了验证。

据悉，纠缠是量子计算和其他前沿技术的核心资源。多维光子图态，特别是团簇态，因其独特的纠缠结构，在量子计量、安全量子通信和基于测量的量子计算等领域具有重要价值。然而，目前多维光子团簇态的生成主要依赖于概率性方法，这严重制约了传统光学生成方法在可扩展性方面的发展。

附：英文原文

Title: Deterministic generation of multidimensional photonic cluster states with a single quantum emitter

Author: Ferreira, Vinicius S., Kim, Gihwan, Butler, Andreas, Pichler, Hannes, Painter, Oskar

Issue&Volume: 2024-02-28

Abstract: Entanglement is a key resource in quantum computing and other prospective technologies. Multidimensional photonic graph states, such as cluster states, have a special entanglement structure that makes them a valuable resource for quantum metrology, secure quantum communication and measurement-based quantum computation. However, to date, the generation of multidimensional photonic cluster states has relied on probabilistic methods that limit the scalability of typical optical generation methods. Here we present an experimental implementation in the microwave domain of a resource-efficient scheme for the deterministic generation of two-dimensional photonic cluster states. Using a coupled resonator array as a slow-light waveguide, a single flux-tunable transmon qubit as a quantum emitter and a second auxiliary transmon as a switchable mirror, we achieve rapid, shaped emission of entangled photon wavepackets, and selective time-delayed feedback of photon wavepackets to the emitter qubit. We use these capabilities to generate a two-dimensional cluster state of four photons with 70% fidelity, as verified by the tomographic reconstruction of the quantum state.

DOI: 10.1038/s41567-024-02408-0

Source: https://www.nature.com/articles/s41567-024-02408-0