Sketch of the considered CKA scenario: At each round of the protocol, a quantum resource is distributed to the parties (in this particular case, a multipartite quantum state). The parties perform local measurements and utilize the outcomes to extract a common secret key. (c) G. Carrara et al./ Phys. Rev. Research

ML4Q PhD student, Giacomo Carrara, published his first paper related to his work supervised by Gláucia Murta in the group of Dagmar Bruß. The group investigates the role of entanglement for the generalization of quantum key distribution to the multipartite scenario. In particular, they ask whether the strongest form of multipartite entanglement, namely, genuine multipartite entanglement, is necessary to establish a conference key.

They show that, surprisingly, a nonzero conference key can be obtained even if the parties share biseparable states in each round of the protocol. They also relate the conference key agreement with entanglement witnesses and show that a nonzero conference key can be interpreted as a nonlinear entanglement witness that detects a class of states which cannot be detected by usual linear entanglement witnesses.

Publication: Giacomo Carrara, Hermann Kampermann, Dagmar Bruß, and Gláucia Murta. Phys. Rev. Research 3, 013264 – Published 19 March 2021 DOI: 10.1103/PhysRevResearch.3.013264

Browse the ML4Q News Archive