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arXiv · 2605.18945

Non-perturbative measurements of two-point functions in quantum field theory

Sebastian Holmén·T. Rick Perche
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Abstract

We present a non-perturbative method through which local probes can access the two-point function of a quantum field within a region of spacetime. By considering a lattice of gapless particle detectors, we identified the probe observables that encode the field's two-point function. We quantify the discrepancies introduced by physical finite-sized interaction regions by performing a spacetime multipole expansion of the smeared two-point function. Our protocol expresses the two-point function entirely in terms of measurable detectors correlations, providing an operational notion of states in QFT.

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Sebastian Holmén, T. Rick Perche. 2026-05-18. Non-perturbative measurements of two-point functions in quantum field theory. https://arxiv.org/abs/2605.18945

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