# Decoherence of the radiation from an accelerated quantum source

## TL;DR

This paper investigates how uniform acceleration of a quantum source causes decoherence in the observed radiation, even when the overall evolution remains unitary, revealing potential insights into reconciling relativity and quantum mechanics.

## Contribution

It demonstrates that accelerated quantum sources induce decoherence in detected radiation despite unitary evolution, highlighting a novel relativistic quantum effect.

## Key findings

- Decoherence occurs in the radiation from an accelerated quantum source.
- Entanglement is also decohered in the two-mode case.
- Decoherence persists even when the global state remains pure.

## Abstract

Decoherence is the process via which quantum superpositions states are reduced to classical mixtures. Decoherence has been predicted for relativistically accelerated quantum systems, however examples to date have involved restricting the detected field modes to particular regions of space-time. If the global state over all space-time is measured then unitarity returns and the decoherence is removed. Here we study a decoherence effect associated with accelerated systems that cannot be explained in this way. In particular we study a uniformly accelerated source of a quantum field state - a single-mode squeezer. Even though the initial state of the field is vacuum (a pure state) and the interaction with the quantum source in the accelerated frame is unitary, we find that the final state detected by inertial observers is decohered, i.e. in a mixed state. This unexpected result may indicate new directions in resolving inconsistencies between relativity and quantum theory. We extend this result to a two-mode state and find entanglement is also decohered.