The exchange interaction between identical qubits in a quantum-information processor gives rise to unitary two-qubit errors. It is shown here that decoherence-free subspaces (DFSs) for collective decoherence undergo Pauli errors under exchange, which, however, do not take the decoherence-free states outside of the DFS. In order to protect DFSs against these errors it is sufficient to employ a recently proposed concatenated DFS quantum-error-correcting code scheme [D. A. Lidar, D. Bacon, and K.B. Whaley, Phys. Rev. Lett. 82, 4556 (1999)].
|Original language||English (US)|
|Number of pages||5|
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|Publication status||Published - Jan 1 2000|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics