Barycentric decomposition for quantum instruments
Quantum Physics
2026-03-03 v1 Mathematical Physics
math.MP
Abstract
We present a barycentric decomposition for quantum instruments whose output space is finite-dimensional and input space is separable. As a special case, we obtain a barycentric decomposition for channels between such spaces and for normalized positive-operator-valued measures in separable Hilbert spaces. This extends the known results by Ali and Chiribella et al. on decompositions of quantum measurements, and formalises the fact that every instrument between finite-dimensional Hilbert spaces can be represented using only finite-outcome instruments.
Keywords
Cite
@article{arxiv.2307.08405,
title = {Barycentric decomposition for quantum instruments},
author = {Juha-Pekka Pellonpää and Erkka Haapasalo and Roope Uola},
journal= {arXiv preprint arXiv:2307.08405},
year = {2026}
}