title: Experimental demonstration of unconditional entanglement swapping for continuous variables.
abstract: The unconditional entanglement swapping for continuous variables is experimentally demonstrated. Two initial entangled states are produced from two nondegenerate optical parametric amplifiers operating at de-amplification. Through implementing the direct measurement of the Bell-state between two optical beams from each amplifier the remaining two optical beams, which have never directly interacted with each other, are entangled. The quantum correlation degrees of 1.23 and 1.12 dB below the shot noise limit for the amplitude and phase quadratures resulting from the entanglement swapping are measured straightly.
authors.affiliation: The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, People's Republic of China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Jia
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Su
authors.forename: Qing
authors.initials: Q
authors.lastname: Pan
authors.forename: Jiangrui
authors.initials: J
authors.lastname: Gao
authors.forename: Changde
authors.initials: C
authors.lastname: Xie
authors.forename: Kunchi
authors.initials: K
authors.lastname: Peng