# Quantum imaging using relativistic detectors

## TL;DR

This paper introduces a quantum imaging framework using relativistic Unruh-DeWitt detectors, enabling the study of imaging processes and correlations in non-inertial reference frames within quantum optics.

## Contribution

It develops a quantum field theory model of SPDC coupled with UDW detectors to analyze imaging and correlations in inertial and non-inertial frames, extending quantum optics to relativistic settings.

## Key findings

- Reconstructed images distinguish inputs better than random guesses.
- Correlations between detectors may not stem from traditional entanglement.
- Contrast in single-pixel imaging exhibits time-dependent behavior.

## Abstract

Imaging in quantum optics (QO) is usually formulated in the languages of quantum mechanics and Fourier optics. While relatively advanced fields, notions such as different reference frames and the degradation of entanglement due to acceleration do not usually feature. Here we propose the idea of using so-called Unruh-DeWitt (UDW) detectors to model the imaging process in QO. In particular, we first present a quantum field theory version of a state describing Spontaneous Parametric Down Conversion (SPDC), one of the principal processes employed to create entangled photons in the laboratory. This state, coupled to UDW detectors, is used to investigate a single-pixel ghost image under both inertial and non-inertial settings, and a two-pixel image under inertial conditions. The reconstructed images obtained for various possible inputs can be distinguished better than a pure guess, hence the formalism can be used to describe imaging between non-inertial frames. We briefly consider the origin of the correlations between the UDW detectors, which don't appear to arise from the usual notion of entanglement. Finally, we find that the contrast between the possible outcomes in the single-pixel case follows a curious coupling time dependent behaviour.