{"id":1226,"date":"2021-02-17T17:28:19","date_gmt":"2021-02-17T15:28:19","guid":{"rendered":"https:\/\/webs.uab.cat\/giq\/seminar\/strict-hierarchy-between-parallel-sequential-and-indefinite-causal-order-strategies-for-channel-discrimination\/"},"modified":"2021-02-17T17:28:19","modified_gmt":"2021-02-17T15:28:19","slug":"strict-hierarchy-between-parallel-sequential-and-indefinite-causal-order-strategies-for-channel-discrimination","status":"publish","type":"seminar","link":"https:\/\/webs.uab.cat\/giq\/seminar\/strict-hierarchy-between-parallel-sequential-and-indefinite-causal-order-strategies-for-channel-discrimination\/","title":{"rendered":"Strict hierarchy between parallel, sequential, and indefinite-causal-order strategies for channel discrimination"},"content":{"rendered":"<p><font face=\"arial, sans-serif\">We will discuss a tester formalism for the task of minimum-error channel discrimination that encompasses both standard parallel and sequential strategies and indefinite-causal-order strategies. We start by applying it to general channels, and discover an instance of a discrimination task of two qubit-qubit channels, an amplitude-damping and a bit-flip channel, for which a sequential strategy outperforms any parallel strategy. We then also show that two classes of strategies evolving&nbsp;indefinite causal order outperform causally ordered ones in the same task, forming a strict hierarchy of performance among all four strategies. Our proof technique employs a general method of computer-assisted proofs. Finally, we turn our attention to the discrimination of unitary channels to also find examples of the advantage of sequential and general strategies in this scenario.<\/font><\/p>\n<p><font face=\"arial, sans-serif\">Based on:&nbsp;<\/font><a data-saferedirecturl=\"https:\/\/www.google.com\/url?q=https:\/\/arxiv.org\/abs\/2011.08300&amp;source=gmail&amp;ust=1618477367381000&amp;usg=AFQjCNGAUOdAbolyOhaa_3AuUR8o4CYT8Q\" href=\"https:\/\/arxiv.org\/abs\/2011.08300\" target=\"_blank\" rel=\"noopener\">arXiv:2011.08300&nbsp;[quant-<wbr \/>ph]<\/a>&nbsp;and an upcoming paper.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We will discuss a tester formalism for the task of minimum-error channel discrimination that encompasses both standard parallel and sequential strategies and indefinite-causal-order strategies. We start by applying it to general channels, and discover an instance of a discrimination task of two qubit-qubit channels, an amplitude-damping and a bit-flip channel, for which a sequential strategy [&hellip;]<\/p>\n","protected":false},"author":20,"featured_media":0,"template":"","class_list":["post-1226","seminar","type-seminar","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/seminar\/1226","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=1226"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}