Phys. Rev. A 63, 022306 (2001) [13 pages]Decoherence-free subspaces for multiple-qubit errors. I. CharacterizationReceived 19 August 1999; revised 6 July 2000; published 17 January 2001 Coherence in an open quantum system is degraded through its interaction with a bath. This decoherence can be avoided by restricting the dynamics of the system to special decoherence-free subspaces. These subspaces are usually constructed under the assumption of spatially symmetric system-bath coupling. Here we show that decoherence-free subspaces may appear without spatial symmetry. Instead, we consider a model of system-bath interactions in which to first order only multiple-qubit coupling to the bath is present, with single-qubit system-bath coupling absent. We derive necessary and sufficient conditions for the appearance of decoherence-free states in this model, and give a number of examples. In a sequel paper we show how to perform universal and fault tolerant quantum computation on the decoherence-free subspaces considered in this paper. © 2001 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevA.63.022306
DOI:
10.1103/PhysRevA.63.022306
PACS:
03.67.Lx, 03.65.Ta, 03.65.Fd, 89.70.+c
See AlsoSee Also: Daniel A. Lidar, Dave Bacon, Julia Kempe, and K. B. Whaley, Decoherence-free subspaces for multiple-qubit errors. II. Universal, fault-tolerant quantum computation, Phys. Rev. A 63, 022307 (2001). |
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