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Protecting quantum information encoded in decoherence-free states against exchange errors

2000; American Physical Society; Volume: 61; Issue: 5 Linguagem: Inglês

10.1103/physreva.61.052307

1538-4446

Daniel A. Lidar, David F. Bacon, Julia Kempe, K. Birgitta Whaley,

Quantum and electron transport phenomena

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. {\bf 82}, 4556 (1999)].