Phys. Rev. B 72, 085335 (2005) [7 pages]Decoherence-free states for charge qubits under local nonuniformityReceived 11 April 2005; revised 22 June 2005; published 18 August 2005 We analyze the robustness of a decoherence-free (DF) subspace and subsystem in charge qubits, when the difference from the collective decoherence measurement condition is large (∼5%) in the long time period, which is applicable for solid-state qubits using as a quantum memory. We solve master equations of up to four charge qubits and a detector as a quantum point contact. We show that robustness of DF states is strongly affected by local nonuniformities. We also discuss the possible two-qubit logical states by exactly solving the master equations. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.72.085335
DOI:
10.1103/PhysRevB.72.085335
PACS:
73.63.Kv, 03.67.Mn, 73.23.−b, 81.07.Ta
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