Schrödinger’s cat just got bigger: quantum physicists create largest ever ‘superposition’
Article Date: 21 January 2026
Article URL: https://www.nature.com/articles/d41586-026-00177-9
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Punchy: a clear, record-breaking experiment that pushes the boundary between quantum and classical realms. If you follow quantum tech or fundamental physics, this is big news — and the paper is worth a closer look for the experimental method alone.
Summary
Researchers at the University of Vienna have produced the largest-ever spatial superposition: clusters of roughly 7,000 sodium atoms (about 8 nanometres across) were placed into a superposition of distinct locations separated by 133 nanometres. Instead of behaving like classical particles, each cluster exhibited wave-like behaviour, spreading through an interferometer made from three laser gratings and producing a detectable interference pattern.
The team ran the experiment at 77 kelvin in ultra-high vacuum and detected interference after the clusters passed the gratings, demonstrating that quantum mechanics still governs objects at scales comparable to large biomolecules or small viruses. The result bears on debates about decoherence and collapse theories and has practical relevance for scaling quantum technologies.
Key Points
- Record: largest spatial superposition to date — clusters of ~7,000 sodium atoms placed in distinct, interfering paths.
- Scale: clusters were ~8 nm wide, with superposed path separations of 133 nm; mass comparable to a protein or small virus particle.
- Method: matter-wave interferometry using three laser-produced gratings at 77 K in ultra-high vacuum enabled clear interference fringes.
- Implication for foundations: pushes the boundary for tests of decoherence and collapse theories that predict a breakdown of quantum behaviour at larger scales.
- Implication for technology: informs feasibility of scaling up quantum systems for computing — if natural collapse happened at smaller scales it would limit large-scale quantum devices.
- Conclusion: for clusters of this size, quantum mechanics remains valid — no unexpected classical transition observed.
Why should I read this?
Quick and honest: if you care about where quantum weirdness stops (or don’t), this is a tidy milestone. It’s a neat, well-executed experiment that edges the “Schrödinger’s cat” thought experiment closer to real stuff — proteins and tiny viruses — and tells us quantum rules still hold. Worth a skim if you like the drama of physics getting weirder at larger sizes.
Context and relevance
This experiment matters for two main reasons. First, it addresses a long-standing philosophical and physical question: how and when does the classical world emerge from quantum rules? By scaling up interfering objects to a mass comparable with biomolecules, the team narrows the window where alternative collapse mechanisms could act.
Second, it has practical relevance for quantum technologies. Building large, coherent quantum states is essential for quantum computing and sensing. Demonstrating that larger clusters maintain quantum coherence helps validate assumptions behind scaling efforts and guides future engineering of quantum systems.