Year: 2026
Type: article
Abstract: The notion of a macroscopic quantum state must be pinned down in order to assess how well experiments probe the large-scale limits of quantum mechanics. However, the issue of quantifying so-called quantum macroscopicity is fraught with multiple approaches having varying interpretations and levels of computability and measurability. Here, we introduce two measures that capture independent macroscopic properties: i) extensive size, measuring the degree of coherence in position or momentum observables relative to atomic-scale units, and ii) entangled size, quantifying the number of entangled subsystems. These measures unify many desirable features of past proposals while having rigorously justified interpretations from quantum information theory in terms of coherence and multipartite entanglement. We demonstrate how to estimate them and obtain lower-bounds using experimental data from micro-mechanical oscillators and diffracting molecules. Notably, we find evidence for genuine multipartite entanglement of 10 5 to 10 7 atoms in recent mechanical superposition states.
Source: Quantum
Authors: Benjamin Yadin, Matteo Fadel
Institutions: University of Siegen, Peking University, ETH Zurich
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $215
Awards: Verbundprojekt: Quantennetzwerke: Korrelationen und Kommunikation - QuKuK -, Teilvorhaben: Netzwerkstrukturen und Quantenzustände, Testing quantum mechanics with bulk acoustic wave resonators, Sensing and Sensibility - Transcending Disciplines for a Responsible Future, Charakterisierung hochdimensionaler Verschränkung und Kohärenz, G2627917216, G3663324400, G3882652674, G5468585985, G7071182864, Aspekte des Quantum Steerings
OpenAlex ID: W4414577882