English

Non-symmetric GHZ states: weighted hypergraph and controlled-unitary graph representations

Quantum Physics 2025-10-02 v2

Abstract

Non-symmetric GHZ states (nn-GHZα_\alpha), defined by unequal superpositions of 00...0>|00...0> and 11...1>|11...1>, naturally emerge in experiments due to decoherence, control errors, and state preparation imperfections. Despite their relevance in quantum communication, relativistic quantum information, and quantum teleportation, these states lack a stabilizer formalism and a graph representation, hindering their theoretical and experimental analysis. We establish a graph-theoretic framework for non-symmetric GHZ states, proving their local unitary (LU) equivalence to two structures: fully connected weighted hypergraphs with controlled-phase interactions and star-shaped controlled-unitary (CU) graphs. While weighted hypergraphs generally lack stabilizer descriptions, we demonstrate that non-symmetric GHZ states can be efficiently stabilized using local operations and a single ancilla, independent of system size. We extend this framework to qudit systems, constructing LU-equivalent weighted qudit hypergraphs and showing that general non-symmetric qudit GHZ states can be described as star-shaped CU graphs. Our results provide a systematic approach to characterizing and stabilizing non-symmetric multipartite entanglement in both qubit and qudit systems, with implications for quantum error correction and networked quantum protocols.

Keywords

Cite

@article{arxiv.2408.02740,
  title  = {Non-symmetric GHZ states: weighted hypergraph and controlled-unitary graph representations},
  author = {Hrachya Zakaryan and Konstantinos-Rafail Revis and Zahra Raissi},
  journal= {arXiv preprint arXiv:2408.02740},
  year   = {2025}
}

Comments

15 pages(Main Text + Supplementary Material), 4 figures. Comments and suggestions are very welcome!

R2 v1 2026-06-28T18:04:39.947Z