  The inevitable existence of static internal imperfections and residual
interactions in some quantum computer architectures result in internal
decoherence, dissipation, and destructive unitary shifts of active algorithms.
By exact numerical simulations we determine the relative importance and origin
of these errors for a Josephson charge qubit quantum computer. In particular we
determine that the dynamics of a CNOT gate interacting with its idle
neighboring qubits via native residual coupling behaves much like a perturbed
kicked top in the exponential decay regime, where fidelity decay is only weakly
dependent on perturbation strength. This means that retroactive removal of gate
errors (whether unitary or non-unitary) may not be possible, and that effective
error correction schemes must operate concurrently with the implementation of
subcomponents of the gate.
