{"id":110084,"date":"2015-08-04T03:00:00","date_gmt":"2015-08-04T00:00:00","guid":{"rendered":"http:\/\/www.fyysika.ee\/?guid=ea40ac2040eb8cf9b3c262b33007d836"},"modified":"2015-08-04T03:00:00","modified_gmt":"2015-08-04T00:00:00","slug":"no-faster-than-light-signaling-implies-linear-evolution-a-re-derivation","status":"publish","type":"post","link":"https:\/\/www.fyysika.ee\/?p=110084","title":{"rendered":"No-faster-than-light-signaling implies linear evolution. A re-derivation"},"content":{"rendered":"<p>There is a growing interest, both from the theoretical as well as experimental side, to test the<br \/>\nvalidity of the quantum superposition principle, and of theories which explicitly violate it by<br \/>\nadding nonlinear terms to the Schr\u00f6dinger equation. We review the original argument elaborated by<br \/>\nGisin (1989 Helv. Phys. Acta 62 363), which shows that the non-superluminal-signaling condition<br \/>\nimplies that the dynamics of the density matrix must be linear. This places very strong constraints<br \/>\non the permissible modifications of the Schr\u00f6dinger equation, since they have to give rise, at the<br \/>\nstatistical level, to a linear evolution for the density matrix. The derivation is done in a<br \/>\nheuristic way here and is appropriate for the students familiar with the textbook quantum mechanics<br \/>\nand the language of density matrices.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>There is a growing interest, both from the theoretical as well as experimental side, to test the<br \/>\nvalidity of the quantum superposition principle, and of theories which explicitly violate it by<br \/>\nadding nonlinear terms to the Schr\u00f6dinger equation. We r&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[178],"tags":[],"class_list":{"0":"post-110084","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-rss-fuusikaharidus","7":"entry"},"_links":{"self":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/110084","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=110084"}],"version-history":[{"count":0,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/110084\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=110084"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=110084"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=110084"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}