title: Experimental observation of quantum correlations in four-wave mixing with a conical pump.
abstract: Generation of multimode quantum states has drawn much attention recently due to its importance for both fundamental science and the future development of quantum technologies. Here, by using a four-wave mixing process with a conical pump beam, we have experimentally observed about -3.8  dB of intensity-difference squeezing between a single-axial probe beam and a conical conjugate beam. The multi-spatial-mode nature of the generated quantum-correlated beams has been shown by comparing the variation tendencies of the intensity-difference noise of the probe and conjugate beams under global attenuation and local cutting attenuation. Due to its compactness, phase-insensitive nature, and easy scalability, our scheme may find potential applications in quantum imaging, quantum information processing, and quantum metrology.
authors.forename: Leiming
authors.initials: L
authors.lastname: Cao
authors.forename: Jinjian
authors.initials: J
authors.lastname: Du
authors.forename: Jingliang
authors.initials: J
authors.lastname: Feng
authors.forename: Zhongzhong
authors.initials: Z
authors.lastname: Qin
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Marino
authors.forename: Mikhail I
authors.initials: MI
authors.lastname: Kolobov
authors.forename: Jietai
authors.initials: J
authors.lastname: Jing