Physically realizable entanglement by local continuous measurements

Eduardo Mascarenhas, Daniel Cavalcanti, Vlatko Vedral, and Marcelo França Santos
Phys. Rev. A 83, 022311 – Published 14 February 2011

Abstract

Quantum systems prepared in pure states evolve into mixtures under environmental action. Continuously realizable ensembles (or physically realizable) are the pure state decompositions of those mixtures that can be generated in time through continuous measurements of the environment. Here, we define continuously realizable entanglement as the average entanglement over realizable ensembles. We search for the measurement strategy to maximize and minimize this quantity through observations on the independent environments that cause two qubits to disentangle in time. We then compare it with the entanglement bounds (entanglement of formation and entanglement of assistance) for the unmonitored system. For some relevant noise sources the maximum realizable entanglement coincides with the upper bound, establishing the scheme as an alternative to protect entanglement. However, for local strategies, the lower bound of the unmonitored system is not reached.

  • Figure
  • Received 15 June 2010

DOI:https://doi.org/10.1103/PhysRevA.83.022311

©2011 American Physical Society

Authors & Affiliations

Eduardo Mascarenhas1,2, Daniel Cavalcanti2, Vlatko Vedral2,3,4, and Marcelo França Santos1,2

  • 1Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Caixa Postal 702, 30123-970, MG, Brazil
  • 2Centre for Quantum Technologies, National University of Singapore, Singapore
  • 3Department of Physics, National University of Singapore, Singapore
  • 4Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom

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Vol. 83, Iss. 2 — February 2011

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