{"id":1199,"date":"2020-02-10T11:20:44","date_gmt":"2020-02-10T09:20:44","guid":{"rendered":"https:\/\/webs.uab.cat\/giq\/seminar\/gaussian-thermal-operations-and-the-limits-of-algorithmic-cooling\/"},"modified":"2020-02-10T11:20:44","modified_gmt":"2020-02-10T09:20:44","slug":"gaussian-thermal-operations-and-the-limits-of-algorithmic-cooling","status":"publish","type":"seminar","link":"https:\/\/webs.uab.cat\/giq\/seminar\/gaussian-thermal-operations-and-the-limits-of-algorithmic-cooling\/","title":{"rendered":"Gaussian Thermal Operations and The Limits of Algorithmic Cooling"},"content":{"rendered":"<p>The recently established resource theory of quantum thermodynamics offers a framework to determine the ultimate possibilities and limitations in the manipulation of quantum states and in the implementation of nanoscale thermal machines. A core endeavour of this programme is to determine under which conditions can a nonequilibrium quantum state be converted into another using thermal operations. Here we settle this question in the important case of Gaussian quantum states and channels. We provide a complete characterisation of Gaussian thermal operations acting on an arbitrary number of bosonic modes, and derive a simple geometric criterion establishing necessary and sufficient conditions for state transformations under such operations in the general single-mode case, encompassing states with nonzero coherence (squeezing) in the energy eigenbasis. Our analysis leads to a no-go result for the technologically relevant task of algorithmic cooling: We show that it is impossible to reduce the entropy of a system coupled to a Gaussian environment below its own or the environmental temperature, by means of a sequence of Gaussian thermal operations interspersed by arbitrary (even non-Gaussian) unitaries. These findings establish fundamental constraints on the usefulness of Gaussian resources for quantum thermodynamic processes.<\/p>\n<p><img decoding=\"async\" alt=\"\" src=\"https:\/\/ssl.gstatic.com\/ui\/v1\/icons\/mail\/images\/cleardot.gif\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The recently established resource theory of quantum thermodynamics offers a framework to determine the ultimate possibilities and limitations in the manipulation of quantum states and in the implementation of nanoscale thermal machines. A core endeavour of this programme is to determine under which conditions can a nonequilibrium quantum state be converted into another using thermal [&hellip;]<\/p>\n","protected":false},"author":20,"featured_media":0,"template":"","class_list":["post-1199","seminar","type-seminar","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/seminar\/1199","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=1199"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}