Causality and signalling in non-compact detector-field interactions

Abstract

In this paper we analyze the problem of "apparent" superluminal signalling and retrocausation that can appear for particle detector models when considering non-compactly supported field-detector interactions in quantum field theory in curved spacetimes and in relativistic quantum information protocols. For this purpose, we define a signalling estimator based on an adapted version of the quantum Fisher information to perturbative regimes. This allows us to study how the internal dynamics of the detectors (for example the gap between the detector energy levels) have an impact on the ability of a particle detectors to communicate with one another. Moreover, we show that, very generally, even for detectors with infinite tails in space and time, if the tails decay exponentially, one can define an effective lightcone, outside of which signalling is negligible. This provides concrete evidence supporting the use of non-compact (but exponentially decaying) detector smearings in protocols of relativistic quantum information.

arXiv comment25 pages, 3 Appendices, 3 Figures. RevTeX 4.2. v2: corrected small typo in original submission

References in corpus (27)

• Entanglement from the vacuum
• How often does the Unruh-DeWitt detector click? Regularisation by a spatial profile
• Entanglement harvesting from the electromagnetic vacuum with hydrogenlike atoms
• Wavepacket detection with the Unruh-DeWitt model
• Considerations on the Unruh Effect: Causality and Regularization
• Causality issues of particle detector models in QFT and Quantum Optics
• Interferometric Unruh detectors for Bose-Einstein condensates
• Quantum delocalization, gauge and quantum optics: The light-matter interaction in relativistic quantum information
• General Relativistic Quantum Optics: Finite-size particle detector models in curved spacetimes
• Information transmission without energy exchange
• A detector-based measurement theory for quantum field theory
• Broken covariance of particle detector models in relativistic quantum information
• Static detectors and circular-geodesic detectors on the Schwarzschild black hole
• Relativistic Quantum Optics: On the relativistic invariance of the light-matter interaction models
• Renormalized Unruh-DeWitt Particle Detector Models for Boson and Fermion Fields
• Unruh-DeWitt detector response along static and circular geodesic trajectories for Schwarzschild-AdS black holes
• Relativistic causality in particle detector models: Faster-than-light signalling and "Impossible measurements"
• Time-of-arrival probabilities for general particle detectors
• Quantum Information Processing and Relativistic Quantum Fields
• The Schwinger Mechanism, the Unruh Effect and the Production of Accelerated Black Holes
• Neutrino flavor oscillations without flavor states
• Dynamics of quantum causal structures
• Communication through quantum fields near a black hole
• On Coherent Delocalization in the Light-Matter Interaction
• Quantum Field Theory based Quantum Information: Measurements and Correlations
• Finite sizes and smooth cutoffs in superconducting circuits
• Complementarity and causal propagation of decoherence by measurement in relativistic quantum field theories

Cited by in corpus (12)

• Fully Relativistic Entanglement Harvesting
• Particle Detectors from Localized Quantum Field Theories
• Quantum entanglement in cosmology
• Preserving quantum information in $f(Q)$ cosmology
• Closed-form expressions for smeared bi-distributions of a massless scalar field: non-perturbative and asymptotic results in relativistic quantum information
• Harvesting Fermionic Field Entanglement in Schwarzschild Spacetime
• Derivative coupling enables genuine entanglement harvesting in causal communication
• Harvesting Contextuality from the Vacuum
• The stress-energy tensor of an Unruh-DeWitt detector
• A relativistic QFT description for the interaction of a spin with a magnetic field
• Invisible extended Unruh-DeWitt detector
• Bipartite and tripartite entanglement in pure dephasing relativistic spin-boson model