Year: 2025
Type: article
Abstract: In the one-way model of measurement-based quantum computation (MBQC), computation proceeds via single-qubit measurements on a resource state.Flow conditions ensure that the overall computation is deterministic in a suitable sense, and are required for efficient translation into quantum circuits.Procedures that rewrite MBQC patterns -e.g. for optimisation, or adapting to hardware constraints -thus need to preserve the existence of flow.Most previous work has focused on rewrites that reduce the number of qubits in the computation, or that introduce new Pauli-measured qubits.Here, we consider the insertion of planar-measured qubits into MBQC patterns, i.e. arbitrary measurements in a plane of the Bloch sphere spanned by a pair of Pauli operators; such measurements are necessary for universal MBQC.We extend the definition of causal flow, previously restricted to XY -measurements only, to also permit Y Z-measurements and derive the conditions under which a Y Z-insertion preserves causal flow.Then we derive conditions for Y Z-insertion into patterns with gflow or Pauli flow, in which case the argument straightforwardly extends to XZ-insertions as well.We also show that the 'vertex splitting' or 'neighbour unfusion' rule previously used in the literature can be derived from Y Z-insertion and pivoting.This work contributes to understanding the broad properties of flow-preserving rewriting in MBQC and in the ZX-calculus more broadly, and it will enable more efficient optimisation, obfuscation, or routing.
DOI: 10.4204/eptcs.426.4
Authors: Miriam Backens, Thomas Perez
Institutions: Centre National de la Recherche Scientifique, Institut national de recherche en sciences et technologies du numérique, Laboratoire Lorrain de Recherche en Informatique et ses Applications, Université de Lorraine, École Polytechnique, Centre de Physique Théorique, Laboratoire d'Informatique de l'École Polytechnique, Institut Polytechnique de Paris
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4413306558