Eliminating the "impossible": Recent progress on local measurement theory for quantum field theory

• URL: http://arxiv.org/abs/2307.08524v2
• Date: Fri, 15 Dec 2023 16:44:56 GMT
• Title: Eliminating the "impossible": Recent progress on local measurement theory for quantum field theory
• Authors: Maria Papageorgiou, Doreen Fraser
• Abstract summary: We investigate the consequences for measurement in quantum field theory (QFT) We review three different approaches to formulating an account of measurement for QFT and analyze their responses to the "impossible measurements" problem.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Arguments by Sorkin arXiv:gr-qc/9302018 and Borsten, Jubb, and Kells arXiv:1912.06141 establish that a natural extension of quantum measurement theory from non-relativistic quantum mechanics to relativistic quantum theory leads to the unacceptable consequence that expectation values in one region depend on which unitary operation is performed in a spacelike separated region. Sorkin labels such scenarios "impossible measurements". We explicitly present these arguments as a no-go result with the logical form of a reductio argument and investigate the consequences for measurement in quantum field theory (QFT). Sorkin-type impossible measurement scenarios clearly illustrate the moral that Microcausality is not by itself sufficient to rule out superluminal signalling in relativistic quantum theories that use L\"uders' rule. We review three different approaches to formulating an account of measurement for QFT and analyze their responses to the "impossible measurements" problem. Two of the approaches are: a measurement theory based on detector models proposed in Polo-G\'omez, Garay, and Mart\'in-Mart\'Inez arXiv:2108.02793 and a measurement framework for algebraic QFT proposed in Fewster and Verch arXiv:1810.06512. Of particular interest for foundations of QFT is that they share common features that may hold general morals about how to represent measurement in QFT. These morals are about the role that dynamics plays in eliminating "impossible measurements", the abandonment of the operational interpretation of local algebras as representing possible operations carried out in a region, and the interpretation of state update rules. Finally, we examine the form that the "impossible measurements" problem takes in histories-based approaches and we discuss the remaining challenges.

Related papers

• Testing trajectory-based determinism via time probability distributions [44.99833362998488]
  Bohmian mechanics (BM) has inherited more predictive power than quantum mechanics (QM) We introduce a prescription for constructing a flight-time probability distribution within generic trajectory-equipped theories. We derive probability distributions that are unreachable by QM.
  arXiv  Detail & Related papers  (2024-04-15T11:36:38Z)
• Embezzling entanglement from quantum fields [41.94295877935867]
  Embezzlement of entanglement refers to the counterintuitive possibility of extracting entangled quantum states from a reference state of an auxiliary system. We uncover a deep connection between the operational task of embezzling entanglement and the mathematical classification of von Neumann algebras.
  arXiv  Detail & Related papers  (2024-01-14T13:58:32Z)
• Towards a measurement theory in QFT: "Impossible" quantum measurements are possible but not ideal [0.0]
  We show that the same problem arises in non-relativistic quantum physics, where joint nonlocal measurements lead to signaling. We develop a non-relativistic quantum information approach developed independently of the impossible measurements in QFT. These considerations could help guide the development of a complete theory of measurement in QFT.
  arXiv  Detail & Related papers  (2023-11-22T19:00:16Z)
• Enhanced Entanglement in the Measurement-Altered Quantum Ising Chain [46.99825956909532]
  Local quantum measurements do not simply disentangle degrees of freedom, but may actually strengthen the entanglement in the system. This paper explores how a finite density of local measurement modifies a given state's entanglement structure.
  arXiv  Detail & Related papers  (2023-10-04T09:51:00Z)
• The measurement postulates of quantum mechanics are not redundant [0.0]
  Masanes, Galley and M"uller argue that the measurement postulates of non-relativistic quantum mechanics follow from the structural postulates. We refute their conclusion, giving explicit examples of non-quantum measurement and state update rules.
  arXiv  Detail & Related papers  (2023-07-12T14:30:36Z)
• Measurement incompatibility is strictly stronger than disturbance [44.99833362998488]
  Heisenberg argued that measurements irreversibly alter the state of the system on which they are acting, causing an irreducible disturbance on subsequent measurements. This article shows that measurement incompatibility is indeed a sufficient condition for irreversibility of measurement disturbance. However, we exhibit a toy theory, termed the minimal classical theory (MCT), that is a counterexample for the converse implication.
  arXiv  Detail & Related papers  (2023-05-26T13:47:00Z)
• Measurement and Probability in Relativistic Quantum Mechanics [0.0]
  This paper provides a relativistic model of measurement, in which the state of the universe is decomposed into decoherent histories of measurements recorded within it. The wave functions that we actually use for such experiments are local reductions of very coarse-grained superpositions of universal eigenstates.
  arXiv  Detail & Related papers  (2022-09-26T04:21:52Z)
• Stochastic approximate state conversion for entanglement and general quantum resource theories [41.94295877935867]
  An important problem in any quantum resource theory is to determine how quantum states can be converted into each other. Very few results have been presented on the intermediate regime between probabilistic and approximate transformations. We show that these bounds imply an upper bound on the rates for various classes of states under probabilistic transformations. We also show that the deterministic version of the single copy bounds can be applied for drawing limitations on the manipulation of quantum channels.
  arXiv  Detail & Related papers  (2021-11-24T17:29:43Z)
• Limits on Relativistic Quantum Measurement [0.0]
  Requiring causality on measurements in quantum field theory seems to impose strong conditions on a self-adjoint operator to be really measurable. Recent publications attempt to deal with this issue by including the apparatus into the formalism. I present measurement theory in AQFT, modelling the apparatus as a quantum field with coupling to the measured system restricted to a region of spacetime.
  arXiv  Detail & Related papers  (2021-09-07T16:47:00Z)
• Causal State Updates in Real Scalar Quantum Field Theory [0.0]
  In relativistic Quantum Field Theory (QFT) ideal measurements of certain observables are physically impossible without violating causality. Here we formulate a necessary and sufficient condition that any measurement must satisfy to respect causality in real scalar QFT. We show how to do this using only causal measurements of smeared fields.
  arXiv  Detail & Related papers  (2021-06-16T18:00:00Z)
• The role of boundary conditions in quantum computations of scattering observables [58.720142291102135]
  Quantum computing may offer the opportunity to simulate strongly-interacting field theories, such as quantum chromodynamics, with physical time evolution. As with present-day calculations, quantum computation strategies still require the restriction to a finite system size. We quantify the volume effects for various $1+1$D Minkowski-signature quantities and show that these can be a significant source of systematic uncertainty.
  arXiv  Detail & Related papers  (2020-07-01T17:43:11Z)

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.