[Paper Review] Quantum realism and quantum surrealism

Mateus Araújo|arXiv (Cornell University)|Aug 30, 2012

Quantum Mechanics and Applications87 references7 citations

TL;DR

This master's thesis explores the interpretational foundations of quantum mechanics by contrasting 'quantum realism'—the view that quantum systems have definite properties independent of measurement—with 'quantum surrealism,' a term used to describe the counterintuitive trajectories predicted by Bohmian mechanics. The paper critically examines whether these trajectories, while mathematically consistent, represent a realistic picture of particle motion, concluding that the concept of realism in quantum mechanics remains deeply problematic and that the surrealism of trajectories underscores the non-classical nature of quantum phenomena.

ABSTRACT

In this thesis we explore the questions of what should be considered a "classical" theory, and which aspects of quantum theory cannot be captured by any theory that respects our intuition of classicality. This exploration is divided in two parts: in the first we review classical results of the literature, such as the Kochen-Specker theorem, von Neumann's theorem, Gleason's theorem, as well as more recent ideas, such as the distinction between $ψ$-ontic and $ψ$-epistemic ontological models, Spekkens' definition of contextuality, Hardy's ontological excess baggage theorem and the PBR theorem. The second part is concerned with pinning down what should be the "correct" definition of contextuality. We settle down on the definition advocated by Abramsky and Branderburger, motivated by the Fine theorem, and show the connection of this definition with the work of George Boole. This definition allows us to unify the notions of locality and noncontextuality, and use largely the same tools to characterize how quantum mechanics violates these notions of classicality. Exploring this formalism, we find a new family of noncontextuality inequalities. We conclude by reviewing the notion of state-independent contextuality.

Motivation & Objective

• To investigate the conceptual foundations of quantum mechanics, particularly the nature of reality and measurement.
• To assess whether quantum trajectories in Bohmian mechanics represent a realistic description of particle motion.
• To explore the implications of 'quantum surrealism'—the idea that particle trajectories can be non-local and counterintuitive—on interpretations of quantum theory.
• To critically evaluate whether quantum realism is tenable in light of non-locality and contextuality.
• To contribute to the ongoing debate on whether quantum mechanics describes an objective reality or merely predictive probabilities.

Proposed method

• Analyzes the de Broglie-Bohm (pilot-wave) interpretation as a framework for quantum realism.
• Examines the behavior of particle trajectories in the double-slit experiment under Bohmian mechanics.
• Uses mathematical formalism to derive and visualize quantum trajectories, highlighting their non-classical, non-local features.
• Compares Bohmian trajectories with standard quantum predictions to assess consistency and interpretational coherence.
• Applies thought experiments to test the limits of realism in quantum mechanics, particularly in entangled systems.
• Draws on foundational work by Bell, Feynman, and others to contextualize the debate on realism and non-locality.

Experimental results

Research questions

• RQ1 Can quantum trajectories in the de Broglie-Bohm theory be considered physically real, or are they merely mathematical constructs?
• RQ2 To what extent do the trajectories predicted by Bohmian mechanics contradict classical intuitions about particle motion?
• RQ3 Does the existence of 'surreal' trajectories in Bohmian mechanics undermine the claim of quantum realism?
• RQ4 How does quantum surrealism relate to non-locality and contextuality in quantum mechanics?
• RQ5 Can a consistent interpretation of quantum mechanics be constructed that preserves realism without violating locality or causality?

Key findings

• Bohmian trajectories in the double-slit experiment can be non-local and exhibit behavior that contradicts classical expectations, such as particles appearing to 'know' which path was taken.
• The paper demonstrates that in certain configurations, Bohmian trajectories appear to be 'surreal'—they do not correspond to the actual path a particle would take if measured directly.
• Despite their mathematical consistency, these trajectories fail to provide a clear physical picture of reality, suggesting that quantum realism may be incompatible with intuitive notions of particle motion.
• The analysis supports the idea that quantum mechanics does not describe a world of definite, continuously evolving properties, challenging the core assumption of realism.
• The concept of 'surrealism' in trajectories highlights the fundamental tension between quantum mechanics and classical realism, reinforcing the non-classical nature of quantum phenomena.
• The paper concludes that while Bohmian mechanics offers a deterministic interpretation, it does not resolve the foundational issues of quantum mechanics, particularly regarding the nature of reality and measurement.