Decoherence-free states for charge qubits under local nonuniformity
Tetsufumi Tanamoto, Shinobu Fujita · Physical Review B · 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 $(\ensuremath{\sim}5%)$ 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.