Real-time feedback control of a mesoscopic superposition
  We show that continuous real-time feedback can be used to track, control, and protect a mesoscopic superposition of two spatially separated wave-packets. The feedback protocol is enabled by an approximate state-estimator, and requires two continuous measurements, performed simultaneously. For nanomechanical and superconducting resonators, both measurements can be implemented by coupling the resonators to superconducting qubits. 
Kurt Jacobs, Justin Finn, Sai Vinjanampathy
quant-ph cond-mat.mes-hall