Resource-efficient generation of continuous-variable Greenberger–Horne–Zeilinger entanglement based on a quantum frequency comb
Juan Li, Peng Liu, Xinghua Li +4 more
Continuous-variable (CV) multipartite entangled states, particularly Greenberger–Horne–Zeilinger (GHZ) states, are an indispensable resource for quantum networks and quantum information processing. Conventional approaches to generating CV GHZ states rely on combining multiple independently prepared squeezed lights through complex interferometric networks, which impose significant challenges in scalability and stability. Here, we experimentally demonstrate a compact and resource-efficient scheme for generating a tripartite CV GHZ state from a single quantum frequency comb produced by a synchronously pumped optical parametric oscillator. By employing multipixel homodyne detection, we simultaneously measure quadrature fluctuations across multiple frequency bands and reconstruct the full multimode covariance matrix in a single measurement. Through eigenmode decomposition, we extract a set of independent squeezed supermodes, which are subsequently transformed via a tailored linear unitary operation implemented in post-processing. Using this approach, we deterministically construct a tripartite GHZ state from three supermodes and verify its entanglement via the van Loock–Furusawa criteria, with the corresponding correlation variances measured to be 0.57, 0.75, and 0.57, all below the shot noise limit. This method effectively realizes a scalable entanglement generation scheme within a single optical beam, eliminating the need for complex interferometric networks. Our results provide a scalable and versatile platform for multimode quantum information processing.
Quantum Review Letters•Jan 1, 2026•0 citations