http://arxiv.org/abs/1407.1950 http://arxiv.org/abs/1402.7140 These sounded promising at least before I noticed that all their experiments were done at about 0.05 kelvin temperature and apparenly they've never managed to build a q-gate, only single qubits. You get a crystal of ultrapure silicon-28 (spin-0 isotope of Si). You put in a phosphorus-31 dopant atom. Different spin states of the dopant atom nucleus & electron store two qubits. Atomic state-transition spectral frequencies can be used to stimulate transitions, thus controlling the state of the qubit. Now you can create an electric field near that dopant atom by charging some metal gate. This "Stark shifts" its spectral frequencies. That way, by charging only the gate you want, you can control only the qubit you want and leave the others alone. Instead of using a phosphorus dopant atom, you can use an "artificial atom" (system with state-transitions) made from a "quantum dot." Can systems with many interacting qubits (via q-gates) thus be built? -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)