Towards local and compositional measurements in quantum field theory

Fuente: arXiv
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Main Authors: Oeckl, Robert, Zampeli, Adamantia
Format: Preprint
Published: 2025
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author Oeckl, Robert
Zampeli, Adamantia
author_facet Oeckl, Robert
Zampeli, Adamantia
contents A universal framework for the joint measurement of multiple localized observables in quantum field theory satisfying spacetime locality and compositionality is still lacking. We present an approach to the problem that is based on the one hand on the positive formalism, an axiomatic framework, where it is clear from the outset that we satisfy locality and compositionality, while also having a consistent probabilistic interpretation. On the other hand, the approach is based on standard tools from quantum field theory, in particular the path integral and the Schwinger-Keldysh formalism. After an overview of the conceptual foundations we introduce the modulus-square construction as a formalization of the measurement process for an important class of observables including quadratic observables. We show that this construction has many of the desired properties, including positivity, locality, single measurement recovery and compositionality. We introduce a renormalization scheme for the measurement of quadratic observables that also satisfies compositionality, in contrast to previous renormalization schemes. We discuss relativistic causality, confirming that measurements in our scheme are indeed localized in the spacetime regions where the underlying observables have support.
format Preprint
id arxiv_https___arxiv_org_abs_2505_10968
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Towards local and compositional measurements in quantum field theory
Oeckl, Robert
Zampeli, Adamantia
High Energy Physics - Theory
Quantum Physics
A universal framework for the joint measurement of multiple localized observables in quantum field theory satisfying spacetime locality and compositionality is still lacking. We present an approach to the problem that is based on the one hand on the positive formalism, an axiomatic framework, where it is clear from the outset that we satisfy locality and compositionality, while also having a consistent probabilistic interpretation. On the other hand, the approach is based on standard tools from quantum field theory, in particular the path integral and the Schwinger-Keldysh formalism. After an overview of the conceptual foundations we introduce the modulus-square construction as a formalization of the measurement process for an important class of observables including quadratic observables. We show that this construction has many of the desired properties, including positivity, locality, single measurement recovery and compositionality. We introduce a renormalization scheme for the measurement of quadratic observables that also satisfies compositionality, in contrast to previous renormalization schemes. We discuss relativistic causality, confirming that measurements in our scheme are indeed localized in the spacetime regions where the underlying observables have support.
title Towards local and compositional measurements in quantum field theory
topic High Energy Physics - Theory
Quantum Physics
url https://arxiv.org/abs/2505.10968