Decoherence as detector of the Unruh effect, II

TL;DR

This work addresses the challenge of experimentally probing the Unruh effect by extending a decoherence-based detector model from a massless scalar field to the real electromagnetic field in Rindler spacetime. The authors derive the electromagnetic decoherence function $\gamma(\tau)$ for a uniformly accelerated two-level detector, regularized by a finite detector size $l$, and show that $e^{-\gamma(\tau)}$ encodes Unruh thermality with a measurable signature at accelerations $a$ on the order of $10^{12}-10^{13}\ \mathrm{m/s^{2}}$. The key result is the closed-form integral expression for $\gamma(\tau)$ and its large-$a\tau$ asymptotics, revealing both a logarithmic-in-time and a linear-in-time Unruh contribution, highly sensitive to the EM coupling $\Lambda_{em}$ and detector size. This EM-field generalization offers a more experimentally viable pathway to indirect Unruh detection, with implications for quantum information, gravity, and the structure of spacetime in noninertial frames; future work will explore alternative couplings and detector geometries to enhance sensitivity.

Abstract

The Unruh effect remains a central topic in quantum field theory, although its direct experimental verification continues to be challenging. Recent efforts have therefore focused on indirect detection strategies in which the Unruh effect emerges through measurable physical processes. In this work, we extend a previously introduced detector model, originally formulated for a massless scalar field, to the electromagnetic field. We show that the decoherence decay rates differ between inertial and accelerated frames. Furthermore, we demonstrate that the characteristic exponential decay associated with the Unruh effect can be observed at lower accelerations than those considered in earlier studies.

Figures (2)

• Figure 1: The exponential decay function for the model detector and the electromagnetic field, $e^{-\gamma(\tau)}$, versus $\tau$ and $a$.
• Figure 2: The exponential decay function for our model detector and the electromagnetic field, $e^{-\gamma(\tau)}$, versus $\tau$. From top to bottom: $a = 0$ (cyan), $a = 1 \cdot 10^{13} \ \textrm{m/s}^2$ (red), $a = 1 \cdot 10^{14} \ \textrm{m/s}^2$ (green), $a = 1 \cdot 10^{15} \ \textrm{m/s}^2$ (orange), $a = 1 \cdot 10^{16} \ \textrm{m/s}^2$ (blue), $a = 1 \cdot 10^{17} \ \textrm{m/s}^2$ (black). Inset: zoom of the main figure.