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Phys. Rev. A 72, 042303 (2005) [14 pages]

Theory of initialization-free decoherence-free subspaces and subsystems

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Alireza Shabani1,* and Daniel A. Lidar2,†
1Physics Department and Center for Quantum Information and Quantum Control, University of Toronto, 60 St. George Street, Toronto, Ontario, Canada M5S 1A7
2Chemical Physics Theory Group, Chemistry Department, and Center for Quantum Information and Quantum Control, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6

Received 8 May 2005; published 3 October 2005

We introduce a generalized theory of decoherence-free subspaces and subsystems (DFSs), which do not require accurate initialization. We derive a set of conditions for the existence of DFSs within this generalized framework. By relaxing the initialization requirement we show that a DFS can tolerate arbitrarily large preparation errors. This has potentially significant implications for experiments involving DFSs, in particular for the experimental implementation, over DFSs, of the large class of quantum algorithms which can function with arbitrary input states.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.72.042303
DOI:
10.1103/PhysRevA.72.042303
PACS:
03.67.Lx, 03.65.Yz, 03.65.Fd

*Present address: Department of Chemistry and Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, CA 90089.

†Present address: Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, CA 90089.

 
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