# A time-frequency approach to relativistic correlations in quantum field theory

## TL;DR

This paper introduces a novel time-frequency formalism, inspired by signal processing and quantum optics, to analyze the response of moving detectors in relativistic quantum fields, revealing insights into entanglement, particle definitions, and non-stationary effects.

## Contribution

It develops a general Wigner-based framework for analyzing non-stationary detector responses in relativistic quantum field theory, bridging signal processing and quantum physics.

## Key findings

- Framework effectively analyzes non-stationary detector responses.
- Reveals how motion deforms excitations and superpositions.
- Provides new perspectives on particle definitions in relativistic settings.

## Abstract

Moving detectors in relativistic quantum field theories reveal the fundamental entangled structure of the vacuum which manifests, for instance, through its thermal character when probed by a uniformly accelerated detector. In this paper, we propose a general formalism inspired both from signal processing and correlation functions of quantum optics to analyze the response of point-like detectors following a generic, non-stationary trajectory. In this context, the Wigner representation of the first-order correlation of the quantum field is a natural time-frequency tool to understand single-detection events. This framework offers a synthetic perspective on the problem of detection in relativistic theory and allows us to analyze various non-stationary situations (adiabatic, periodic) and how excitations and superpositions are deformed by motion. It opens up interesting perspective on the issue of the definition of particles.