Experimental Optimum Maximum-Confidence Discrimination and Optimum   Unambiguous Discrimination of Two Mixed Single-Photon States
  We present an experimental implementation of optimum measurements for quantum state discrimination. Optimum maximum-confidence discrimination and optimum unambiguous discrimination of two mixed single-photon polarization states were performed. For the latter the states of rank two in a four-dimensional Hilbert space are prepared using both path and polarization encoding. Linear optics and single photons from a true single-photon source based on a semiconductor quantum dot are utilized. 
Gesine A. Steudle, Sebastian Knauer, Ulrike Herzog, Erik Stock,   Vladimir A. Haisler, Dieter Bimberg, Oliver Benson
quant-ph