Experimental measurement of a nonlinear entanglement witness by hyperentangling two-qubit states
Experimental measurement of a nonlinear entanglement witness by hyperentangling two-qubit states
We demonstrate that nonlinear entanglement witnesses can be made particularly useful for entanglement detection in hyperentangled or multilevel states. We test this idea experimentally on the platform of linear optics using a hyperentangled state of two photons. Instead of several simultaneous copies of two-photon entangled states, one can directly measure …