A strong no-go theorem on the Wigner's friend paradox

• URL: http://arxiv.org/abs/1907.05607v4
• Date: Wed, 15 Mar 2023 08:28:55 GMT
• Title: A strong no-go theorem on the Wigner's friend paradox
• Authors: Kok-Wei Bong, An\'ibal Utreras-Alarc\'on, Farzad Ghafari, Yeong-Cherng Liang, Nora Tischler, Eric G. Cavalcanti, Geoff J. Pryde and Howard M. Wiseman
• Abstract summary: We prove that if quantum evolution is controllable on the scale of an observer, then one of 'No-Superdeterminism', 'Locality' or 'Absoluteness of Observed Events' must be false. We show that although the violation of Bell-type inequalities in such scenarios is not in general sufficient to demonstrate the contradiction between those three assumptions, new inequalities can be derived in a theory-independent manner.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Does quantum theory apply at all scales, including that of observers? New light on this fundamental question has recently been shed through a resurgence of interest in the long-standing Wigner's friend paradox. This is a thought experiment addressing the quantum measurement problem -- the difficulty of reconciling the (unitary, deterministic) evolution of isolated systems and the (non-unitary, probabilistic) state update after a measurement. Here, by building on a scenario with two separated but entangled friends introduced by Brukner, we prove that if quantum evolution is controllable on the scale of an observer, then one of 'No-Superdeterminism', 'Locality' or 'Absoluteness of Observed Events' -- that every observed event exists absolutely, not relatively -- must be false. We show that although the violation of Bell-type inequalities in such scenarios is not in general sufficient to demonstrate the contradiction between those three assumptions, new inequalities can be derived in a theory-independent manner, that are violated by quantum correlations. This is demonstrated in a proof-of-principle experiment where a photon's path is deemed an observer. We discuss how this new theorem places strictly stronger constraints on physical reality than Bell's theorem.

Related papers

• Logic meets Wigner's Friend (and their Friends) [49.1574468325115]
  We take a fresh look at Wigner's Friend thought-experiment and some of its more recent variants and extensions. We discuss various solutions proposed in the literature, focusing on a few questions.
  arXiv  Detail & Related papers  (2023-07-04T13:31:56Z)
• Events in quantum mechanics are maximally non-absolute [0.9176056742068814]
  We prove that quantum correlations can be maximally non-absolute according to both quantifiers. We show that chained Bell inequalities (and relaxations thereof) are also valid constraints for Wigner's experiment.
  arXiv  Detail & Related papers  (2021-12-19T21:15:16Z)
• Demonstration of quantum correlations that are incompatible with absoluteness of measurement [0.0]
  We exploit the tension between the two dynamics of quantum theory (QT) in the Wigner's Friend thought experiment. We show that the set of probabilities obtainable for NoM is strictly larger than the set obtainable for AoM.
  arXiv  Detail & Related papers  (2021-07-18T13:32:32Z)
• Quantum indistinguishability through exchangeable desirable gambles [69.62715388742298]
  Two particles are identical if all their intrinsic properties, such as spin and charge, are the same. Quantum mechanics is seen as a normative and algorithmic theory guiding an agent to assess her subjective beliefs represented as (coherent) sets of gambles. We show how sets of exchangeable observables (gambles) may be updated after a measurement and discuss the issue of defining entanglement for indistinguishable particle systems.
  arXiv  Detail & Related papers  (2021-05-10T13:11:59Z)
• Observers of quantum systems cannot agree to disagree [55.41644538483948]
  We ask whether agreement between observers can serve as a physical principle that must hold for any theory of the world. We construct examples of (postquantum) no-signaling boxes where observers can agree to disagree.
  arXiv  Detail & Related papers  (2021-02-17T19:00:04Z)
• Impossibility of creating a superposition of unknown quantum states [16.467540842571328]
  We show that the existence of a protocol that superposes two unknown pure states with nonzero probability leads to violation of other no-go theorems. Such a protocol can be used to perform certain state discrimination and cloning tasks that are forbidden in quantum theory.
  arXiv  Detail & Related papers  (2020-11-04T13:25:42Z)
• Quantum erasing the memory of Wigner's friend [0.0]
  Wigner's friend paradox concerns one of the most puzzling problems of quantum mechanics. At the core of the paradox lies the description of an observer and the object it measures as a closed system obeying the Schr"odinger equation. We argue that the three apparently incompatible properties used to question the consistency of quantum mechanics correspond to two logically distinct contexts.
  arXiv  Detail & Related papers  (2020-09-21T14:24:58Z)
• A no-go theorem for the persistent reality of Wigner's friend's perception [0.0]
  We formulate a no-go theorem for the persistent reality of Wigner's friend's perception. In a Wigner's friend scenario, there is no joint probability distribution for the friend's perceived measurement outcomes at two different times. We briefly discuss which of the theorem's assumptions are more likely to be dropped within various popular interpretations of quantum mechanics.
  arXiv  Detail & Related papers  (2020-09-20T18:56:52Z)
• Non-Boolean Hidden Variables model reproduces Quantum Mechanics' predictions for Bell's experiment [91.3755431537592]
  Theory aimed to violate Bell's inequalities must start by giving up Boolean logic. "Hard" problem is to predict the time values when single particles are detected. "Soft" problem is to explain the violation of Bell's inequalities within (non-Boolean) Local Realism.
  arXiv  Detail & Related papers  (2020-05-20T21:46:35Z)
• Bell's theorem for trajectories [62.997667081978825]
  A trajectory is not an outcome of a quantum measurement, in the sense that there is no observable associated with it. We show how to overcome this problem by considering a special case of our generic inequality that can be experimentally tested point-by-point in time.
  arXiv  Detail & Related papers  (2020-01-03T01:40:44Z)

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.