Entanglement verification for quantum-key-distribution systems with an underlying bipartite qubit-mode structure

Johannes Rigas, Otfried Gühne, and Norbert Lütkenhaus
Phys. Rev. A 73, 012341 – Published 30 January 2006

Abstract

We consider entanglement detection for quantum-key-distribution systems that use two signal states and continuous-variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify entanglement, we introduce an object that combines the covariance matrix of the mode with the density matrix of the qubit. We derive necessary separability criteria for this scenario. These criteria can be readily evaluated using semidefinite programming and we apply them to the specific quantum key distribution protocol.

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  • Received 17 October 2005

DOI:https://doi.org/10.1103/PhysRevA.73.012341

©2006 American Physical Society

Authors & Affiliations

Johannes Rigas1, Otfried Gühne2, and Norbert Lütkenhaus1

  • 1Quantum Information Theory Group, Institut für Theoretische Physik I, and Max-Planck Research Group, Institute of Optics, Information and Photonics, Universität Erlangen-Nürnberg, Staudtstraße 7/B2, 91058 Erlangen, Germany
  • 2Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, A-6020 Innsbruck, Austria

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Vol. 73, Iss. 1 — January 2006

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