Circuit-quantum electrodynamics with direct magnetic coupling to   single-atom spin qubits in isotopically enriched 28Si
  Recent advances in silicon nanofabrication have allowed the manipulation of spin qubits that are extremely isolated from noise sources, being therefore the semiconductor equivalent of single atoms in vacuum. We investigate the possibility of directly coupling an electron spin qubit to a superconducting resonator magnetic vacuum field. By using resonators modified to increase the vacuum magnetic field at the qubit location, and isotopically purified 28Si substrates, it is possible to achieve coupling rates faster than the single spin dephasing. This opens up new avenues for circuit-quantum electrodynamics with spins, and provides a pathway for dispersive read-out of spin qubits via superconducting resonators. 
Guilherme Tosi, Fahd A. Mohiyaddin, Hans Huebl and Andrea Morello
cond-mat.mes-hall quant-ph