Experimental observation of entanglement duality for identical particles

J. -J. Ma, X. -X. Yuan, C. Zu, X. -Y. Chang, P. -Y. Hou, L. -M. Duan

Published 2014-08-22Version 1

It was shown recently that entanglement of identical particles has a feature called dualism [Phys. Rev. Lett. 110, 140404 (2013)], which is fundamentally connected with quantum indistinguishability. Here we report an experiment that observes the entanglement duality for the fi?rst time with two identical photons, which manifest polarization entanglement when labeled by diff?erent paths or path entanglement when labeled by polarization states. By adjusting the mismatch in frequency or arrival time of the entangled photons, we tune the photon indistinguishability from quantum to classical limit and observe that the entanglement duality disappears under emergence of classical distinguishability, con?rming it as a characteristic feature of quantum indistinguishable particles.