title: Continuous-variable entanglement measurement using an unbalanced Mach-Zehnder interferometer.
abstract: We propose a simple scheme using an unbalanced Mach-Zehnder interferometer to directly measure the entangled beams with correlation of amplitude quadratures and anticorrelation of phase quadratures. In the experiment, we use two fibers with lengths of 2 and 50 m to construct the interferometer. The correlation variances of amplitude difference and phase sum of the entangled beams from a nondegenerate optical parametric amplifier are simultaneously measured to be 1.79 and 1.62 dB below the shot noise limit, respectively. Such a simple and convenient method has potential applications in quantum measurements.
authors.forename: Chuanqing
authors.initials: C
authors.lastname: Xia
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.forename: Jiale
authors.initials: J
authors.lastname: Guo
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Xiao