Towards optimized suppression of dephasing in systems subject to pulse timing constraints

Thomas E. Hodgson, Lorenza Viola, and Irene D’Amico
Phys. Rev. A 81, 062321 – Published 16 June 2010

Abstract

We investigate the effectiveness of different dynamical decoupling protocols for storage of a single qubit in the presence of a purely dephasing bosonic bath, with emphasis on comparing quantum coherence preservation under uniform versus nonuniform delay times between pulses. In the limit of instantaneous bit-flip pulses, this is accomplished by establishing a different representation of the controlled qubit evolution, where the decoherence behavior after an arbitrary number of pulses is directly expressed in terms of the uncontrolled decoherence function. In particular, analytical expressions are obtained for approximation of the long- and short-term coherence behavior for both Ohmic and supra-Ohmic environments. By focusing on the realistic case of pure dephasing in an excitonic qubit, we quantitatively assess the impact of physical constraints on achievable pulse separations, and show that little advantage of high-level decoupling schemes based on concatenated or optimal design may be expected if pulses cannot be applied sufficiently fast. In such constrained scenarios, we demonstrate how simple modifications of repeated periodic-echo protocols can offer significantly improved coherence preservation in realistic parameter regimes. We expect similar conclusions to be relevant to other constrained qubit devices exposed to quantum or classical phase noise.

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  • Received 10 December 2009

DOI:https://doi.org/10.1103/PhysRevA.81.062321

©2010 American Physical Society

Authors & Affiliations

Thomas E. Hodgson1, Lorenza Viola2, and Irene D’Amico1

  • 1Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
  • 2Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, New Hampshire 03755, USA

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Issue

Vol. 81, Iss. 6 — June 2010

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