Browsing by Author "Xie, Tianqi"

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    Direct Temporal Mode Measurement for the Characterization of Temporally Multiplexed High Dimensional Quantum Entanglement in Continuous Variables
    (APS, 2020-05-29) Huo, Nan; Liu, Yuhong; Li, Jiamin; Cui, Liang; Chen, Xin; Palivela, Rithwik; Xie, Tianqi; Li, Xiaoying; Ou, Z. Y.; Physics, School of Science
    Field-orthogonal temporal mode analysis of optical fields has recently been developed for a new framework of quantum information science. However, so far, the exact profiles of the temporal modes are not known, which makes it difficult to achieve mode selection and demultiplexing. Here, we report a novel method that measures directly the exact form of the temporal modes. This, in turn, enables us to make mode-orthogonal homodyne detection with mode-matched local oscillators. We apply the method to a pulse-pumped, specially engineered fiber parametric amplifier and demonstrate temporally multiplexed multidimensional quantum entanglement of continuous variables in telecom wavelength. The temporal mode characterization technique can be generalized to other pulse-excited systems to find their eigenmodes for multiplexing in the temporal domain.
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    Generation of pure-state single photons with high heralding efficiency by using a three-stage nonlinear interferometer
    (American Institute of Physics, 2020-05-18) Li, Jiamin; Su, Jie; Cui, Liang; Xie, Tianqi; Ou, Z. Y.; Li, Xiaoying; Physics, School of Science
    We experimentally study a fiber-based three-stage nonlinear interferometer and demonstrate its application in generating heralded single photons with high efficiency and purity by spectral engineering. We obtain a heralding efficiency of 90% at a brightness of 0.039 photons/pulse. The purity of the source is checked by two-photon Hong-Ou-Mandel interference with a visibility of 95 ± 6% (after correcting Raman scattering and multi-pair events). Our investigation indicates that the heralded source of single photons produced by the three-stage nonlinear interferometer has the advantages of high purity, high heralding efficiency, high brightness, and flexibility in wavelength and bandwidth selection.