Challenging local realism with human choices (1805.04431v3)

Abstract: A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human free will' could be used rigorously to ensure unpredictability in Bell tests. Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons, single atoms, atomic ensembles, and superconducting devices. Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bipartite and tripartite scenarios. Project outcomes include closing thefreedom-of-choice loophole' (the possibility that the setting choices are influenced by `hidden variables' to correlate with the particle properties), the utilization of video-game methods for rapid collection of human generated randomness, and the use of networking techniques for global participation in experimental science.

Challenging Local Realism with Human Choices

The paper "Challenging local realism with human choices" presented by the BIG Bell Test Collaboration investigates fundamental questions in quantum physics, specifically the principle of local realism, using human-generated random inputs. Local realism posits that objects have pre-defined properties independent of observation, and no information can be transmitted faster than the speed of light. The paper leverages the Bell test, which juxtaposes empirical results against the theoretical predictions of local realism.

To conduct this paper, approximately 100,000 human participants engaged in generating random binary choices through an online video game. This human-generated randomness was distributed via a scalable web platform to 12 laboratories across five continents. Within these labs, experiments employed various quantum systems including photons, single atoms, atomic ensembles, and superconducting devices.

Experimental Design and Execution

The Bell test requires ensuring three core elements: spatial entanglement, efficient and rapid detection, and unpredictability in measurement settings. While technological advancements meet the former two, unpredictability remained traditionally hampered by reliance on physical devices, creating vulnerabilities in Bell tests. These vulnerabilities are known as loopholes, notably the freedom-of-choice loophole, where hidden variables could potentially influence the selection of measurement settings.

Human free will, argued by Bell himself, offers a resolution by ensuring unpredictability devoid of assumptions inherent in physics-based random generators. In this experiment, human choices served as the fundamental random variable influencing measurement settings—a remarkable departure from past studies utilizing physical devices like spontaneous emission sources or quantum random number generators for setting choices.

Results and Statistical Significance

The collaboration executed 13 different experimental setups to scrutinize local realism. These results revealed correlations significantly contradicting local realist predictions across bipartite and tripartite scenarios. Notably, strong statistical significance supported these findings, with some experiments closing multiple loopholes simultaneously, including freedom-of-choice and detection-efficiency loopholes.

The statistical robustness of this endeavor is manifested in the high standard deviation values guarded in these results. For instance, several setups demonstrated violations of CHSH and other Bell inequalities by more than 100 standard deviations, an empirical rejection of local realistic interpretations.

Implications and Future Directions

The implications of this research extend beyond theoretical discourse to practical applications in quantum information science. The demonstration of inherent randomness, as substantiated by non-local quantum correlations, is pivotal to secure quantum communications. Furthermore, using human choices in experimental designs paves a path to novel gamification strategies, fostering global scientific engagement and spread.

Elevation of free choice in experimental settings promises advancements in future explorations of quantum mechanics where randomness and measurement independence are indispensable. There is scope for further refinement in integrating human-derived randomness, particularly addressing biases in human inputs.

In summary, this research represents a potent exploration into longstanding questions about the nature of reality and opens avenues for further sophisticated inquiries within quantum physics that inform both theoretical understanding and practical innovations. The leveraging of human choice as a key variable represents an exemplary blend of scientific inquiry with societal engagement, setting a methodological precedent for participatory scientific research.