Feedback control of a solid-state qubit using high-fidelity projective   measurement
  We demonstrate feedback control of a superconducting transmon qubit using discrete, projective measurement and conditional coherent driving. Feedback realizes a fast and deterministic qubit reset to a target state with 2.4% error averaged over input superposition states, and cooling of the transmon from 16% spurious excitation to 3%. This closed-loop qubit control is necessary for measurement-based protocols such as quantum error correction and teleportation. 
D. Rist\`e, C. C. Bultink, K. W. Lehnert, L. DiCarlo
cond-mat.mes-hall quant-ph