Hawking radiation for detectors in superposition of locations outside a black hole

TL;DR

This paper investigates how a quantum superposition of detector trajectories near a black hole affects the perception of Hawking radiation, revealing quantum coherences and their dependence on the detector's path.

Contribution

It introduces a novel analysis of Hawking radiation detection by a superposed trajectory, highlighting quantum coherences in the detector's final state.

Findings

Detection coherences depend on the superposed trajectories.

Quantum field states exhibit distinguishability based on detector paths.

Results relate spatial particle distribution to quantum detector states.

Abstract

Hawking radiation is the proposed thermal black-body radiation of quantum nature emitted from a black hole. One common way to give an account of Hawking radiation is to consider a detector that follows a static trajectory in the vicinity of a black hole and interacts with the quantum field of the radiation. In the present work, we study the Hawking radiation perceived by a detector that follows a quantum superposition of static trajectories in Schwarzschild spacetime, instead of a unique well-defined trajectory. We analyze the quantum state of the detector after the interaction with a massless real scalar field. We find that for certain trajectories and excitation levels, there are non-vanishing coherences in the final state of the detector. We then examine the dependence of these coherences on the trajectories followed by the detector and relate them to the distinguishability of the different possible states in which the field is left after the excitation of the detector. We interpret our results in terms of the spatial distribution and propagation of particles of the quantum field.