Quantum Discord and the Power of One Qubit

Animesh Datta, Anil Shaji, and Carlton M. Caves
Phys. Rev. Lett. 100, 050502 – Published 5 February 2008

Abstract

We use quantum discord to characterize the correlations present in the model called deterministic quantum computation with one quantum bit (DQC1), introduced by Knill and Laflamme [Phys. Rev. Lett. 81, 5672 (1998)]. The model involves a collection of qubits in the completely mixed state coupled to a single control qubit that has nonzero purity. The initial state, operations, and measurements in the model all point to a natural bipartite split between the control qubit and the mixed ones. Although there is no entanglement between these two parts, we show that the quantum discord across this split is nonzero for typical instances of the DQC1 ciruit. Nonzero values of discord indicate the presence of nonclassical correlations. We propose quantum discord as figure of merit for characterizing the resources present in this computational model.

  • Figure
  • Received 4 September 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.050502

©2008 American Physical Society

Authors & Affiliations

Animesh Datta*, Anil Shaji, and Carlton M. Caves

  • Department of Physics and Astronomy, MSC07-4220, University of New Mexico, Albuquerque, New Mexico 87131, USA

  • *animesh@unm.edu

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Issue

Vol. 100, Iss. 5 — 8 February 2008

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