Causality and signalling in non-compact detector-field interactions

• URL: http://arxiv.org/abs/2305.07756v2
• Date: Tue, 16 May 2023 04:22:52 GMT
• Title: Causality and signalling in non-compact detector-field interactions
• Authors: Jos\'e de Ram\'on, Maria Papageorgiou and Eduardo Mart\'in-Mart\'inez
• Abstract summary: "apparent" superluminal signalling and retrocausation can appear for particle detector models. We show that, even for detectors with infinite tails in space and time, if the tails decay exponentially, one can define an effective lightcone.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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.

Related papers

• Closed-form expressions for smeared bi-distributions of a massless scalar field: non-perturbative and asymptotic results in relativistic quantum information [0.0]
  We study localized quantum systems which interact with a quantum field in spacetime regions. We find the entanglement that can be acquired by probes which interact in Gaussian spacetime regions. We revisit the case of two gapless detectors and show that the detectors can become entangled if there is two smeared-way signalling between their interaction regions.
  arXiv  Detail & Related papers  (2023-12-20T19:00:01Z)
• How to harness high-dimensional temporal entanglement, using limited interferometry setups [62.997667081978825]
  We develop the first complete analysis of high-dimensional entanglement in the polarization-time-domain. We show how to efficiently certify relevant density matrix elements and security parameters for Quantum Key Distribution. We propose a novel setup that can further enhance the noise resistance of free-space quantum communication.
  arXiv  Detail & Related papers  (2023-08-08T17:44:43Z)
• Suppressing Amplitude Damping in Trapped Ions: Discrete Weak Measurements for a Non-unitary Probabilistic Noise Filter [62.997667081978825]
  We introduce a low-overhead protocol to reverse this degradation. We present two trapped-ion schemes for the implementation of a non-unitary probabilistic filter against amplitude damping noise. This filter can be understood as a protocol for single-copy quasi-distillation.
  arXiv  Detail & Related papers  (2022-09-06T18:18:41Z)
• Tracing Information Flow from Open Quantum Systems [52.77024349608834]
  We use photons in a waveguide array to implement a quantum simulation of the coupling of a qubit with a low-dimensional discrete environment. Using the trace distance between quantum states as a measure of information, we analyze different types of information transfer.
  arXiv  Detail & Related papers  (2021-03-22T16:38:31Z)
• Mid-infrared homodyne balanced detector for quantum light characterization [52.77024349608834]
  We present the characterization of a novel balanced homodyne detector operating in the mid-infrared. We discuss the experimental results with a view to possible applications to quantum technologies, such as free-space quantum communication.
  arXiv  Detail & Related papers  (2021-03-16T11:08:50Z)
• Relativistic causality in particle detector models: Faster-than-light signalling and "Impossible measurements" [0.0]
  We study the relation between faster-than-light signaling and the causal factorization of the dynamics for multiple detector-field interactions. We show in what way spatially extended non-relativistic detector models predict superluminal propagation of the field's initial conditions. We discuss the validity of measurements in QFT when performed with non-relativistic particle detectors.
  arXiv  Detail & Related papers  (2021-02-05T20:18:29Z)
• Broken covariance of particle detector models in relativistic quantum information [0.0]
  We show that the predictions of spatially smeared particle detectors coupled to quantum fields are not generally covariant outside the pointlike limit. We analyze how the breakdown of covariance affects typical detector models in quantum field theory such as the Unruh-DeWitt model.
  arXiv  Detail & Related papers  (2020-06-22T18:00:03Z)
• Quantum metamaterial for nondestructive microwave photon counting [52.77024349608834]
  We introduce a single-photon detector design operating in the microwave domain based on a weakly nonlinear metamaterial. We show that the single-photon detection fidelity increases with the length of the metamaterial to approach one at experimentally realistic lengths. In stark contrast to conventional photon detectors operating in the optical domain, the photon is not destroyed by the detection and the photon wavepacket is minimally disturbed.
  arXiv  Detail & Related papers  (2020-05-13T18:00:03Z)
• Thermality, causality and the quantum-controlled Unruh-deWitt detector [0.0]
  We prepare a detector in a quantum-controlled superposition of trajectories, and study its response to the field in finite-temperature Minkowski spacetime and an expanding de Sitter universe. Unlike a detector on a classical path which cannot distinguish these spacetimes, the superposed detector can do so by acquiring nonlocal information about the geometric and causal structure of its environment.
  arXiv  Detail & Related papers  (2020-05-08T09:01:02Z)
• Quantum noise protects quantum classifiers against adversaries [120.08771960032033]
  Noise in quantum information processing is often viewed as a disruptive and difficult-to-avoid feature, especially in near-term quantum technologies. We show that by taking advantage of depolarisation noise in quantum circuits for classification, a robustness bound against adversaries can be derived. This is the first quantum protocol that can be used against the most general adversaries.
  arXiv  Detail & Related papers  (2020-03-20T17:56:14Z)
• Quantum Temporal Superposition: the case of QFT [0.0]
  We consider what happens when a quantum-controlled superposition of detectors at different space-time points is used to probe the correlations of the field. We show that, due to quantum interference effects, two detectors can gain information on field correlations which would not be otherwise accessible.
  arXiv  Detail & Related papers  (2020-02-14T19:00:00Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.