Qubit ZooSummary
Proposes the flip-flop qubit: encoding quantum information in the combined electron-nuclear spin states of a phosphorus donor in silicon. Electric dipole coupling between qubits enables interaction over ~200 nm (vs. ~15 nm for exchange), relaxing fabrication precision by an order of magnitude. Predicts gate fidelities exceeding fault-tolerance thresholds. Suggests coupling to superconducting resonators for macroscopic-distance entanglement.