Exploiting quantum parallelism of entanglement for a complete   experimental quantum characterization of a single qubit device
  We present the first full experimental quantum tomographic characterization of a single-qubit device achieved with a single entangled input state. The entangled input state plays the role of all possible input states in quantum parallel on the tested device. The method can be trivially extended to any n-qubits device by just replicating the whole experimental setup n times. 
Francesco De Martini, Andrea Mazzei, Marco Ricci, Giacomo Mauro   D'Ariano