{"id":711714,"date":"2026-01-21T22:24:13","date_gmt":"2026-01-21T22:24:13","guid":{"rendered":"https:\/\/www.europesays.com\/uk\/711714\/"},"modified":"2026-01-21T22:24:13","modified_gmt":"2026-01-21T22:24:13","slug":"quantum-physicists-create-largest-ever-superposition","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/uk\/711714\/","title":{"rendered":"quantum physicists create largest ever \u2018superposition\u2019"},"content":{"rendered":"

\"A<\/p>\n

Large objects, including cats, don\u2019t show quantum effects. But physicists aren\u2019t sure where the size limit lies. Credit: Getty<\/p>\n

Schr\u00f6dinger\u2019s cat just got a little bit fatter. Physicists have created the largest ever \u2018superposition\u2019 \u2014 a quantum state in which an object exists in a haze of possible locations at once.<\/p>\n

A team based at the University of Vienna put individual clusters of around 7,000 atoms of sodium metal some 8 nanometres wide into a superposition of different locations, each spaced 133 nanometres apart. Rather than shoot through the experimental set up like a billiard ball, each chunky cluster behaved like a wave, spreading out into a superposition of spatially distinct paths and then interfering to form a pattern researchers could detect.<\/p>\n

\u201cIt\u2019s a fantastic result,\u201d says Sandra Eibenberger-Arias, a physicist at the Fritz Haber Institute in Berlin.<\/p>\n

\"\"<\/p>\n

Physicists disagree wildly on what quantum mechanics says about reality, Nature survey shows<\/p>\n

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Quantum theory doesn\u2019t put a limit on how big a superposition can be, but everyday objects clearly do not behave in a quantum way, she explains. This experiment \u2014 which puts an object as massive as a protein or small virus particle into a superposition \u2014 is helping to answer the \u201cbig, almost philosophical question of \u2018is there a transition between the quantum and classical?\u2019\u201d she says. The authors \u201cshow that, at least for clusters of this size, quantum mechanics is still valid\u201d.<\/p>\n

The experiment, described in Nature on 21 January1<\/a>, is of practical importance, too, says Giulia Rubino, a quantum physicist at the University of Bristol, UK. Quantum computers will ultimately need to maintain perhaps millions of objects in a large quantum state to perform useful calculations. If nature were to make systems collapse past a certain point, and that scale was smaller than what is needed to make a quantum computer,, \u201cthen that\u2019s problematic,\u201d she says.<\/p>\n

Superposition size limit<\/p>\n

Physicists have long debated how the classical, everyday world emerges from an underlying quantum one. Quantum theory \u201cnever states it stops working above a certain mass or size\u201d, says Sebastian Pedalino, a physicist at the University of Vienna and a co-author of the study.<\/p>\n

In 1935, the Austrian physicist Erwin Schr\u00f6dinger showed the absurdity of common interpretations of quantum mechanics with his famous cat-based thought experiment. The cat is put into a box with vial of poison, which will be released if a radioactive atom decays. If the box remains isolated from its environment, the atom exists in a superposition of both decayed and not-decayed, and until observed, the cat is an undefined state of both dead and alive.<\/p>\n

\"\"<\/p>\n

\u2018Levitating\u2019 nanoparticles could push the limits of quantum entanglement<\/p>\n

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In the real world, objects eventually become too complex or interact too much to maintain a superposition, an idea known as decoherence<\/a>. But there are also extensions to quantum mechanics, known as collapse theories, that suggest that beyond a certain point, a system will inevitably reduce to a classical state, even in isolation. These theories were picked by 4% of researchers as their favourite interpretation of quantum mechanics in a 2025 Nature survey<\/a>. \u201cThe only way to answer this question is by scaling up” quantum experiments, says Rubino.<\/p>\n

To do this, Pedalino and his team generated a beam of clusters at 77 degrees kelvin (-196 \u00baC) in an ultra-high vacuum. The researchers put the beam through an interferometer consisting of three gratings constructed with laser beams. The first channelled the clusters through narrow gaps, from which they spread out and travelled in sync as waves; they then passed through a second set of slits that made the waves interfere in a distinctive pattern, which could be detected using the final grating.<\/p>\n","protected":false},"excerpt":{"rendered":"Large objects, including cats, don\u2019t show quantum effects. But physicists aren\u2019t sure where the size limit lies. Credit:…\n","protected":false},"author":2,"featured_media":711715,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[3965,3966,11112,70,16,15],"class_list":{"0":"post-711714","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-humanities-and-social-sciences","9":"tag-multidisciplinary","10":"tag-quantum-physics","11":"tag-science","12":"tag-uk","13":"tag-united-kingdom"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/115935436204798467","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/711714","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=711714"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/711714\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/711715"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=711714"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=711714"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=711714"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}