Unruh effect for detectors in superposition of accelerations

Luis C. Barbado (Corresponding author), Esteban Castro-Ruiz (Corresponding author), Luca Apadula (Corresponding author), Časlav Brukner (Corresponding author)

Publications: Contribution to journalArticlePeer Reviewed


The Unruh effect is the phenomenon that accelerated observers detect particles even when inertial observers experience the vacuum state. In particular, uniformly accelerated observers are predicted to measure thermal radiation that is proportional to the acceleration. Here we consider the Unruh effect for a detector that follows a quantum superposition of different accelerated trajectories in Minkowski spacetime. More precisely, we analyze the excitations of a pointlike multilevel particle detector coupled to a massless real scalar field and moving in the superposition of accelerated trajectories. We find that the state of the detector excitations is, in general, not a mere (convex) mixture of the thermal spectrum characteristics of the Unruh effect for each trajectory with well-defined acceleration separately. Rather, for certain trajectories and excitation levels, and upon the measurement of the trajectory state, the state of the detector excitations features in addition off-diagonal terms. The off-diagonal terms of these "superpositions of thermal states" are related to the distinguishability of the different possible states in which the field is left after its interaction with detector's internal degrees of the freedom.

Original languageEnglish
Article number045002
Pages (from-to)045002
Number of pages16
JournalPhysical Review D
Publication statusPublished - 5 Aug 2020

Austrian Fields of Science 2012

  • 103024 Quantum field theory
  • 103028 Theory of relativity


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