{"id":110672,"date":"2015-07-21T14:27:24","date_gmt":"2015-07-21T18:27:24","guid":{"rendered":"http:\/\/www.rochester.edu\/newscenter\/?p=110672"},"modified":"2022-12-06T14:38:55","modified_gmt":"2022-12-06T19:38:55","slug":"drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672","status":"publish","type":"post","link":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/","title":{"rendered":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary"},"content":{"rendered":"

Quantum theory is one of the great achievements of 20th<\/sup> century science, yet physicists have struggled to find a clear boundary between our everyday world and what Albert Einstein called the \u201cspooky\u201d features of the quantum world, including cats that could be both alive and dead, and photons that can communicate with each other across space instantaneously.<\/p>\n

For the past 60 years, the best guide to that boundary has been a theorem called Bell\u2019s Inequality, but now a new paper shows <\/a>that Bell\u2019s Inequality is not the guidepost it was believed to be, which means that as the world of quantum computing brings quantum strangeness closer to our daily lives, we understand the frontiers of that world less well than scientists have thought.<\/p>\n

In the new paper, published in the July 20 edition of Optica<\/em>, University of Rochester researchers show that a classical beam of light that would be expected to obey Bell\u2019s Inequality can fail this test in the lab, if the beam is properly prepared to have a particular feature: entanglement.<\/p>\n

Not only does Bell\u2019s test not serve to define the boundary, the new findings don’t push the boundary deeper into the quantum realm but do just the opposite. They show that some features of the real world must share a key ingredient of the quantum domain. This key ingredient is called entanglement, exactly the feature of quantum physics that Einstein labeled as spooky. According to Joseph Eberly, professor of physics and one of the paper\u2019s authors, it now appears that Bell’s test only distinguishes those systems that are entangled from those that are not. It does not distinguish whether they are \u201cclassical\u201d or quantum. In the forthcoming paper the Rochester researchers explain how entanglement can be found in something as ordinary as a beam of light.<\/p>\n

Eberly explained that \u201cit takes two to tangle.\u201d For example, think about two hands clapping regularly. What you can be sure of is that when the right hand is moving to the right, the left hand is moving to the left, and vice versa. But if you were asked to guess without listening or looking whether at some moment the right hand was moving to the right, or maybe to the left, you wouldn’t know. But you would still know that whatever the right hand was doing at that time, the left hand would be doing the opposite. The ability to know for sure about a common property without knowing anything for sure about an individual property is the essence of perfect entanglement.<\/p>\n

Eberly added that many think of entanglement as a quantum feature because \u201cSchrodinger coined the term \u2018entanglement\u2019 to refer to his famous cat scenario.\u201d But their experiment shows that some features of the \u201creal\u201d world must share a key ingredient of Schrodinger\u2019s Cat domain: entanglement.<\/p>\n

The existence of classical entanglement was pointed out in 1980, but Eberly explained that it didn\u2019t seem a very interesting concept, so it wasn\u2019t fully explored. As opposed to quantum entanglement, classical entanglement happens within one system. The effect is all local: there is no action at a distance, none of the \u201cspookiness.\u201d<\/p>\n

With this result, Eberly and his colleagues have shown experimentally \u201cthat the border is not where it\u2019s usually thought to be, and moreover that Bell\u2019s Inequalities should no longer be used to define the boundary.\u201d<\/p>\n

Eberly\u2019s co-authors are Xiao-Feng Qian, Bethany Little and Professor John C. Howell.<\/p>\n

The authors acknowledge funding from the Defense Advanced Research Projects Agency (DARPA)\u00a0and the National Science Foundation (NSF).<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

The best guide to the boundary between our everyday world and the \u201cspooky\u201d features of the quantum world has been a theorem called Bell\u2019s Inequality, but now a new paper shows that we understand the frontiers of that quantum world less well than scientists have thought.<\/p>\n","protected":false},"author":6,"featured_media":111112,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[116],"tags":[18662,17762,18572,16072],"class_list":["post-110672","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-sci-tech","tag-department-of-physics-and-astronomy","tag-quantum-science","tag-research-finding","tag-school-of-arts-and-sciences"],"acf":[],"yoast_head":"\nDrawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary\" \/>\n<meta property=\"og:description\" content=\"The best guide to the boundary between our everyday world and the \u201cspooky\u201d features of the quantum world has been a theorem called Bell\u2019s Inequality, but now a new paper shows that we understand the frontiers of that quantum world less well than scientists have thought.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/\" \/>\n<meta property=\"og:site_name\" content=\"News Center\" \/>\n<meta property=\"article:published_time\" content=\"2015-07-21T18:27:24+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2022-12-06T19:38:55+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"999\" \/>\n\t<meta property=\"og:image:height\" content=\"600\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Leonor Sierra\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@leonor_sierra\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Leonor Sierra\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/\"},\"author\":{\"name\":\"Leonor Sierra\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/#\\\/schema\\\/person\\\/b7147819f5697bc51d79e734e5a9efcf\"},\"headline\":\"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary\",\"datePublished\":\"2015-07-21T18:27:24+00:00\",\"dateModified\":\"2022-12-06T19:38:55+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/\"},\"wordCount\":614,\"image\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/wp-content\\\/uploads\\\/2015\\\/07\\\/fea-shordingers-cat.jpg\",\"keywords\":[\"Department of Physics and Astronomy\",\"quantum science\",\"research finding\",\"School of Arts and Sciences\"],\"articleSection\":[\"Science & Technology\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/\",\"url\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/\",\"name\":\"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/wp-content\\\/uploads\\\/2015\\\/07\\\/fea-shordingers-cat.jpg\",\"datePublished\":\"2015-07-21T18:27:24+00:00\",\"dateModified\":\"2022-12-06T19:38:55+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/#\\\/schema\\\/person\\\/b7147819f5697bc51d79e734e5a9efcf\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#primaryimage\",\"url\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/wp-content\\\/uploads\\\/2015\\\/07\\\/fea-shordingers-cat.jpg\",\"contentUrl\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/wp-content\\\/uploads\\\/2015\\\/07\\\/fea-shordingers-cat.jpg\",\"width\":999,\"height\":600,\"caption\":\"extreme close-up of a cat with a mathematical formula printed on its face\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/#website\",\"url\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/\",\"name\":\"News Center\",\"description\":\"University of Rochester\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/#\\\/schema\\\/person\\\/b7147819f5697bc51d79e734e5a9efcf\",\"name\":\"Leonor Sierra\",\"description\":\"Leonor Sierra is press officer for science and engineering. She covers computer science, electrical and computer engineering, laboratory for laser energetics, optics, mechanical engineering, physics and astronomy, and the Office of the Dean of Engineering and Applied Sciences.\",\"sameAs\":[\"https:\\\/\\\/x.com\\\/leonor_sierra\"],\"url\":\"https:\\\/\\\/www.rochester.edu\\\/newscenter\\\/author\\\/lsierra\\\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/","og_locale":"en_US","og_type":"article","og_title":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary","og_description":"The best guide to the boundary between our everyday world and the \u201cspooky\u201d features of the quantum world has been a theorem called Bell\u2019s Inequality, but now a new paper shows that we understand the frontiers of that quantum world less well than scientists have thought.","og_url":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/","og_site_name":"News Center","article_published_time":"2015-07-21T18:27:24+00:00","article_modified_time":"2022-12-06T19:38:55+00:00","og_image":[{"url":"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg","width":999,"height":600,"type":"image\/jpeg"}],"author":"Leonor Sierra","twitter_card":"summary_large_image","twitter_creator":"@leonor_sierra","twitter_misc":{"Written by":"Leonor Sierra","Est. reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#article","isPartOf":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/"},"author":{"name":"Leonor Sierra","@id":"https:\/\/www.rochester.edu\/newscenter\/#\/schema\/person\/b7147819f5697bc51d79e734e5a9efcf"},"headline":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary","datePublished":"2015-07-21T18:27:24+00:00","dateModified":"2022-12-06T19:38:55+00:00","mainEntityOfPage":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/"},"wordCount":614,"image":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#primaryimage"},"thumbnailUrl":"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg","keywords":["Department of Physics and Astronomy","quantum science","research finding","School of Arts and Sciences"],"articleSection":["Science & Technology"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/","url":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/","name":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary","isPartOf":{"@id":"https:\/\/www.rochester.edu\/newscenter\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#primaryimage"},"image":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#primaryimage"},"thumbnailUrl":"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg","datePublished":"2015-07-21T18:27:24+00:00","dateModified":"2022-12-06T19:38:55+00:00","author":{"@id":"https:\/\/www.rochester.edu\/newscenter\/#\/schema\/person\/b7147819f5697bc51d79e734e5a9efcf"},"breadcrumb":{"@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#primaryimage","url":"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg","contentUrl":"https:\/\/www.rochester.edu\/newscenter\/wp-content\/uploads\/2015\/07\/fea-shordingers-cat.jpg","width":999,"height":600,"caption":"extreme close-up of a cat with a mathematical formula printed on its face"},{"@type":"BreadcrumbList","@id":"https:\/\/www.rochester.edu\/newscenter\/drawing-a-line-between-quantum-and-classical-world-bells-inequality-fails-as-a-test-of-the-boundary-110672\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.rochester.edu\/newscenter\/"},{"@type":"ListItem","position":2,"name":"Drawing a line between quantum and classical: Bell\u2019s Inequality fails test as boundary"}]},{"@type":"WebSite","@id":"https:\/\/www.rochester.edu\/newscenter\/#website","url":"https:\/\/www.rochester.edu\/newscenter\/","name":"News Center","description":"University of Rochester","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.rochester.edu\/newscenter\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/www.rochester.edu\/newscenter\/#\/schema\/person\/b7147819f5697bc51d79e734e5a9efcf","name":"Leonor Sierra","description":"Leonor Sierra is press officer for science and engineering. She covers computer science, electrical and computer engineering, laboratory for laser energetics, optics, mechanical engineering, physics and astronomy, and the Office of the Dean of Engineering and Applied Sciences.","sameAs":["https:\/\/x.com\/leonor_sierra"],"url":"https:\/\/www.rochester.edu\/newscenter\/author\/lsierra\/"}]}},"_links":{"self":[{"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/posts\/110672","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/comments?post=110672"}],"version-history":[{"count":2,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/posts\/110672\/revisions"}],"predecessor-version":[{"id":543832,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/posts\/110672\/revisions\/543832"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/media\/111112"}],"wp:attachment":[{"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/media?parent=110672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/categories?post=110672"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rochester.edu\/newscenter\/wp-json\/wp\/v2\/tags?post=110672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}