{"id":1069,"date":"2016-05-16T17:55:30","date_gmt":"2016-05-16T15:55:30","guid":{"rendered":"https:\/\/webs.uab.cat\/giq\/seminar\/size-macroscopic-superpositions-dictated-quantum-mechanics-itself\/"},"modified":"2016-05-16T17:55:30","modified_gmt":"2016-05-16T15:55:30","slug":"size-macroscopic-superpositions-dictated-quantum-mechanics-itself","status":"publish","type":"seminar","link":"https:\/\/webs.uab.cat\/giq\/seminar\/size-macroscopic-superpositions-dictated-quantum-mechanics-itself\/","title":{"rendered":"The size of macroscopic superpositions is dictated by quantum mechanics itself"},"content":{"rendered":"<div>There is nothing in the principles of quantum mechanics that excludes the possibility of preparing macrsocopic objects (such as cats, mugs, or even planets) in a superposition of two, or more, classically distinct states. &nbsp;And yet we never observe such macroscopic superpositions in our everyday experience. &nbsp;Several proposals have been put forth that attempt to explain this phenomenon: the most famous of these proposals are modifications to the Schrodinger equation to account for the effects of gravity (the so-called gravitational induced decoherence), and einselection, which deals with the issue by arguing that such macroscopic states are extremely volatile to the effects of environment induced decoherence.<\/div>\n<div>&nbsp;<\/div>\n<div>In this seminar I will present some preliminary results from ongoing work, in collaboration with Pavel Sekatski and Wolfgang D\u00fcr from the University of Innsbruck, that takes a simpler approach to the problem. &nbsp;Namely, we ask whether the size of macroscopic superpositions can be accounted for by quantum mechanics itself, without invoking extra assumptions on the effects of gravity or environmental decoherence. &nbsp;One startling result from our approach is the following: &nbsp;if one wants to prepare Schr\u00f6dinger\u2019s famous cat, then one would require a reference frame roughly the size of the Earth. &nbsp;More generally, in order to prepare the GHZ state of N qubits (be it photons or spins) one requires a physical system\u2014acting as a \u00abclassical\u00bb reference frame relative to which the GHZ state is prepared\u2014whose size is at least quadratic in N. &nbsp;Finally, I will explore some connections between the resource theories of coherence, reference frames, and themrodynamics, to the problem of quantifying macroscopic superpositions<\/div>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>There is nothing in the principles of quantum mechanics that excludes the possibility of preparing macrsocopic objects (such as cats, mugs, or even planets) in a superposition of two, or more, classically distinct states. &nbsp;And yet we never observe such macroscopic superpositions in our everyday experience. &nbsp;Several proposals have been put forth that attempt to [&hellip;]<\/p>\n","protected":false},"author":20,"featured_media":0,"template":"","class_list":["post-1069","seminar","type-seminar","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/seminar\/1069","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/seminar"}],"about":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/types\/seminar"}],"author":[{"embeddable":true,"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/users\/20"}],"wp:attachment":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/media?parent=1069"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}