Extremal Quantum Correlations: Experimental Study with Two-qubit States
  We explore experimentally the space of two-qubit quantum correlated mixed states, including frontier ones as defined by the use of quantum discord and von Neumann entropy. Our experimental setup is flexible enough to allow for the high-quality generation of a vast variety of states. We address quantitatively the relation between quantum discord and a recently suggested alternative measure of quantum correlations. 
Andrea Chiuri, Giuseppe Vallone, Mauro Paternostro, Paolo Mataloni
quant-ph