  We combine elements of the 1998 quantum computing proposals by Privman,
Vagner and Kventsel, and by Kane, with the new idea of nuclear-spin qubit
interactions mediated indirectly via the bound outer electrons of impurity
atoms whose nuclear spins 1/2 are the qubits. These electrons, in turn,
interact via the two-dimensional electron gas in the quantum Hall effect
regime. The resulting quantum computing scheme retains all the gate-control and
measurement aspects of the proposal by Kane, but allows qubit spacing at
distances of order 100 nm, attainable with the present-day
semiconductor-heterostructure device technologies.
