Barycentric decomposition for quantum instruments
: Pellonpää Juha-Pekka, Haapasalo Erkka, Uola Roope
Publisher: IOP Publishing Ltd
: BRISTOL
: 2024
: Journal of Physics A: Mathematical and Theoretical
: JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
: J PHYS A-MATH THEOR
: 095302
: 57
: 9
: 20
: 1751-8113
: 1751-8121
DOI: https://doi.org/10.1088/1751-8121/ad233c(external)
: https://10.1088/1751-8121/ad233c(external)
: https://research.utu.fi/converis/portal/detail/Publication/387392222(external)
: https://arxiv.org/abs/2307.08405(external)
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 formalizes the fact that every instrument between finite-dimensional Hilbert spaces can be represented using only finite-outcome instruments.