Quantum Interference of 7000 atom sodium nanoparticles
Scientists have observed small metal spheres simultaneously in two places. The experiment rigorously tests quantum mechanics at unprecedented macroscopic scales.
In an advancement for quantum interferometry, researchers from the University of Vienna have demonstrated matter-wave interference with sodium nanoparticles exceeding 7,000 atoms, delocalised over 133 nanometres, more than ten times their diameter. This is a superposition similar to the Schrodinger's Cat thought experiment, and achieves an unprecedented macroscopicity, outstripping previous records by an order of magnitude, and rigourously testing macrorealist modifications to quantum mechanics.
The experiment used a Talbot-Lau setup with three 266 nanometre ultraviolet standing-wave gratings spaced at 0.983 m. The team sourced cryogenic sodium clusters at velocities around 160 m/s yielding de Broglie wavelengths down to 10 femtometres. The first and third gratings act as photodepletion masks, ionising clusters in the antinodes, while the second grating imparts a phase shift via induced dipoles. Bayesian analysis of raw data falsifies minimal macrorealist models, affirming unmodified Schrodinger dynamics. This extends quantum delocalisation to metallic nanoparticles, a novel class bridging molecular and mesoscopic regimes.
It is possible to study a Schrodinger's Virus
Unlike cryogenic resonators or levitated optics, the free-flight coherence probes gravitational and stochastic collapse theories with unprecedented sensitivity. For heavier clusters, visibilities reached 66 per cent. Though near classical limits, velocity reduction to 25 m/s should push the quantum distinction further. The platform for the experiment is versatile enough to accommodate metals, dielectrics and potentially biological nanomaterials such as viroids or proteins. The experiment paves the way for potential tests of equivalence principles and force sensing in delocalised states. As de Broglie wavelengths shrink, this experiment charts a path to macroscale superpositions, probing the quantum-classical boundary with atomic precision. A paper describing the research has been published in Nature.