{"id":1076,"date":"2016-07-05T10:58:38","date_gmt":"2016-07-05T08:58:38","guid":{"rendered":"https:\/\/webs.uab.cat\/giq\/seminar\/converse-bounds-private-communication-over-quantum-channels\/"},"modified":"2016-07-05T10:58:38","modified_gmt":"2016-07-05T08:58:38","slug":"converse-bounds-private-communication-over-quantum-channels","status":"publish","type":"seminar","link":"https:\/\/webs.uab.cat\/giq\/seminar\/converse-bounds-private-communication-over-quantum-channels\/","title":{"rendered":"Converse bounds for private communication over quantum channels"},"content":{"rendered":"

We establish several <\/span>converse<\/span> <\/span>bounds<\/span> on the private transmission capabilities of a quantum channel. The main conceptual development builds firmly on the notion of a private state [Horodecki et al., PRL 94, 160502 (2005)], which is a powerful, uniquely quantum method for simplifying the tripartite picture of privacy involving local operations and public classical communication to a bipartite picture of quantum privacy involving local operations and classical communication. This approach has previously led to some of the strongest upper <\/span>bounds<\/span> on secret key rates, including the squashed entanglement and the relative entropy of entanglement. Here we use this approach along with a “privacy test” to establish a general meta-<\/span>converse<\/span> <\/span>bound<\/span> for private communication, which has a number of applications. The meta-<\/span>converse<\/span> allows for proving that any quantum channel’s relative entropy of entanglement is a strong <\/span>converse<\/span> rate for private communication. For covariant channels, the meta-<\/span>converse<\/span> also leads to second-order expansions of relative entropy of entanglement <\/span>bounds<\/span> for private communication rates. For such channels, the <\/span>bounds<\/span> also apply to the private communication setting in which the sender and receiver are assisted by unlimited public classical communication, and as such, they are relevant for establishing various <\/span>converse<\/span> <\/span>bounds<\/span> for quantum key distribution protocols conducted over these channels. We find precise characterizations for several channels of interest and apply the methods to establish several <\/span>converse<\/span> <\/span>bounds<\/span> on the private transmission capabilities of all phase-insensitive bosonic channels. Joint work with Mario Berta and Marco Tomamichel from <\/span>http:\/\/arxiv.org\/abs\/1602.08898<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

We establish several converse bounds on the private transmission capabilities of a quantum channel. The main conceptual development builds firmly on the notion of a private state [Horodecki et al., PRL 94, 160502 (2005)], which is a powerful, uniquely quantum method for simplifying the tripartite picture of privacy involving local operations and public classical communication to a bipartite […]<\/p>\n","protected":false},"author":20,"featured_media":0,"template":"","class_list":["post-1076","seminar","type-seminar","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/webs.uab.cat\/giq\/wp-json\/wp\/v2\/seminar\/1076","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=1076"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}