Abstract
We assess the most macroscopic matter-wave experiments to date as to the extent to which they probe the quantum-classical boundary by demonstrating interference of heavy molecules and cold atomic ensembles. To this end, we consider a rigorous Bayesian test protocol for a parametrized set of hypothetical modifications of quantum theory, including well-studied spontaneous collapse models, that destroy superpositions and reinstate macrorealism. The range of modification parameters ruled out by the measurement events quantifies the macroscopicity of a quantum experiment, while the shape of the posterior distribution resulting from the Bayesian update reveals how conclusive the data are at testing macrorealism. This protocol may serve as a guide for the design of future matter-wave experiments ever closer to truly macroscopic scales.
Highlights
Matter-wave interference is one of the key observations that validate quantum mechanics and challenge macrorealism [1] and our classical perception of everyday life
We demonstrate how to employ this hypothesis test in the most relevant macroscopic matter-wave scenarios: near-field Talbot-Lau interferometry
We analyzed the most recent matter-wave interference experiments with atoms, molecules, and BECs regarding their capability to probe the quantum-classical transition by ruling out minimal macrorealistic modifications (MMM) of quantum theory
Summary
Matter-wave interference is one of the key observations that validate quantum mechanics and challenge macrorealism [1] and our classical perception of everyday life. There are always unaccounted sources of noise and decoherence in the experiment so that both the quantum and the classical model are incomplete, and the measurement data will likely fit neither One can alleviate this problem by instead considering a continuous hypothesis test against a set of minimal macrorealist modifications (MMM) of quantum mechanics [22]. These models augment the Schrödinger equation by a parametrized stochastic process that destroys superpositions above a certain size, time, and mass threshold, while preserving them on the microscopic scale and fulfilling minimal consistency requirements [23].
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