Decoherence-free quantum information in the presence of dynamical evolution

Peter G. Brooke, James D. Cresser, and Manas K. Patra
Phys. Rev. A 77, 062313 – Published 11 June 2008

Abstract

We analyze decoherence-free (DF) quantum information in the presence of an arbitrary non-nearest-neighbor bath-induced system Hamiltonian using a Markovian master equation. We show that the most appropriate encoding for N qubits is probably contained within the 29N excitation subspace. We give a time scale over which one would expect to apply other methods to correct for the system Hamiltonian. In order to remain applicable to experiment, we then focus on small systems, and present examples of DF quantum information for three and four qubits. We give an encoding for four qubits that, while quantum information remains in the two-excitation subspace, protects against an arbitrary bath-induced system Hamiltonian. Although our results are general to any system of qubits that satisfies our assumptions, throughout the paper we use dipole-coupled qubits as an example physical system.

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  • Received 28 November 2007

DOI:https://doi.org/10.1103/PhysRevA.77.062313

©2008 American Physical Society

Authors & Affiliations

Peter G. Brooke1,*, James D. Cresser1, and Manas K. Patra2,3

  • 1Centre for Quantum Computer Technology and Department of Physics, Macquarie University, Sydney, New South Wales, Australia, 2109
  • 2Department of Computing and Mathematics, University of Western Sydney, Locked Bag 1797, Penrith South DC, New South Wales, Australia, 1797
  • 3Department of Computer Science,University of York, Heslington, York, United Kingdom, YO10 5DD

  • *pgb@ics.mq.edu.au

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Vol. 77, Iss. 6 — June 2008

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