Experimental test of nonlocal causality

  title={Experimental test of nonlocal causality},
  author={Martin Ringbauer and Christina Giarmatzi and Rafael Chaves and Fabio Costa and Andrew G. White and Alessandro Fedrizzi},
  journal={Science Advances},
Causation at a distance does not explain quantum correlations. Explaining observations in terms of causes and effects is central to empirical science. However, correlations between entangled quantum particles seem to defy such an explanation. This implies that some of the fundamental assumptions of causal explanations have to give way. We consider a relaxation of one of these assumptions, Bell’s local causality, by allowing outcome dependence: a direct causal influence between the outcomes of… 

Experimental test of quantum causal influences

Since Bell’s theorem, it is known that local realism fails to explain quantum phenomena. Bell inequality violations manifestly show the incompatibility of quantum theory with classical notions of

Quantum violation of an instrumental test

It is shown that quantum effects imply radically different predictions in the instrumental scenario, and quantum correlations violate the instrumental test, a common statistical method used to estimate the strength of causal relationships between two variables.

Experimental violation of local causality in a quantum network

This work investigates a quantum network consisting of three spatially separated nodes whose correlations are mediated by two distinct sources, and experimentally witness the emergence of the so-called non-bilocal correlations by violating a Bell-like inequality under the fair-sampling assumption.

Experimental verification of an indefinite causal order

Researchers report the first decisive demonstration of a process with an indefinite causal order, and experimentally determine a causal witness, demonstrating by almost 7 SDs that the experimentally implemented process does not have a definite causal order.

Causal reappraisal of the quantum three-box paradox

Quantum three box paradox is a prototypical example of some bizarre predictions for intermediate measurements made on preand post-selected systems. Although in principle those effects can be

Quantum causal influence

We introduce a framework to study the emergence of time and causal structure in quantum many-body systems. In doing so, we consider quantum states which encode spacetime dynamics, and develop

Experimental Test of a Classical Causal Model for Quantum Correlations

  • C. Giarmatzi
  • Physics
    Rethinking Causality in Quantum Mechanics
  • 2019
We experimentally test a causal model that can explain Bell correlations—with a causal link between the outcomes. We find insufficient evidence that this model holds. With the same setup, we also

Quantum Steering Beyond Instrumental Causal Networks.

It is proved that steering alone is enough to maximize the robustness of noninstrumentality-naturally arises, and imply that quantum theory admits a stronger form of steering than known until now, with fundamental as well as practical potential implications.

Simulation of Quantum Correlation Functions is not Sufficient Resource to Describe Quantum Entanglement

The Bell theorem expresses that quantum mechanics is not a local-realistic theory, which is often interpreted as nonlocality of the nature. This result has led to this belief that nonlocality and

Conditions for Lorentz-invariant superluminal information transfer without signaling

It is shown that a basic argument discussing the allegedly paradox time ordering of events in EPR-type two-particle experiments falls short of taking into account the contextuality of the experimental setup, and under which circumstances superluminal information transfer (but not signaling) may be compatible with a Lorentz-invariant theory.




The quantum extension of causal analysis has shown a rich picture of the subsystem causal connections, where the usual intuitive approach is hampered more commonly. The direction of causal connection

Information-theoretic implications of quantum causal structures.

A general algorithm for computing information-theoretic constraints on the correlations that can arise from a given causal structure, where it allows for quantum systems as well as classical random variables.

The lesson of causal discovery algorithms for quantum correlations: causal explanations of Bell-inequality violations require fine-tuning

The need for fine-tuning for most of the causal mechanisms that have been proposed to underlie Bell correlations, including superluminal causal influences, superdeterminism (that is, a denial of freedom of choice of settings), and retrocausal influences which do not introduce causal cycles are demonstrated.

Significant-Loophole-Free Test of Bell's Theorem with Entangled Photons.

A Bell test is reported that closes the most significant of loopholes that provide loopholes for a local realist explanation of quantum mechanics, using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors.

Beyond Bell's theorem: correlation scenarios

This work considers scenarios which feature several sources, but no choice of measurement for the observers, and describes examples of (quantum) non-locality in some of these scenarios, while posing many open problems along the way.

Unifying framework for relaxations of the causal assumptions in Bell's theorem.

A conceptual and computational framework for treating quantum mechanical correlations, which employs the language of Bayesian networks to systematically construct alternative causal structures and bound the degree of relaxation using quantitative measures that originate from the mathematical theory of causality.

Measurements on the reality of the wavefunction

Quantum mechanics is an outstandingly successful description of nature, underpinning fields from biology through chemistry to physics. At its heart is the quantum wavefunction, the central tool for

Beyond Bell’s Theorem II: Scenarios with Arbitrary Causal Structure

It is found that it is possible to talk about classical correlations, quantum correlations and other kinds of correlations on any directed acyclic graph, and this captures various extensions of Bell scenarios that have been considered in the literature.

Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres

The data imply statistically significant rejection of the local-realist null hypothesis and could be used for testing less-conventional theories, and for implementing device-independent quantum-secure communication and randomness certification.


THE paradox of Einstein, Podolsky and Rosen [1] was advanced as an argument that quantum mechanics could not be a complete theory but should be supplemented by additional variables. These additional