Fiber-based Heralded Single Photon Source At Telecom-band

An ideal source of single photons emits one and only one photon in each time, which is a crucial resource for exploring the quantum nature of light and also a essential tool for quantum information processing and high-precision measurement. Based on the correlated photon pairs generated from the spontaneous four-wave mixing parametric process in the fibre, telecom-band heralded single photon is obtained. Pure waveguide mode, low transmission loss and high coupling efficiency of the fiber are beneficial for improving the heralding efficiency and mode purity of the single photon.High-quality correlated photon pairs is the precondition to create the heralded single photon. Firstly, utilizing the spontaneous four-wave mixing in dispersion-shifted fibre, the photon pairs are produced by pumping a fibre Sagnac loop and a piece of straight fibre, respectively, and the features of two setup are pointed out. Meanwhile, the spectral of photon pairs in dispersion-shifted fibre is experimentally investigated, the results indicate signal and idler photon pairs are spectral correlated and using the narrow-band optical filter is a feasible way to acquire the pure state single photon. Afterwards, the purity, brightness and coherence of photon pair are characterized. Then, the fourth-order interference of independent fiber-based thermal field is demonstrated, and the interference visibility is closed to the theoretical limited value, showing photons from fibre source can be viewed as a single spatial and temporal mode. Finally, producing the photon pairs from highly nonlinear fibre is researched.Additionally, we present the first, to the best of our knowledge, telecom-band heralded single photon source based on dispersion-shifted fibre and produce the single-mode photon. Moreover, we describes the second-order correlation function, heralding efficiency, photon pair production rate of the source and further analyze the influence of the filter bandwidth, noise photons and temperature. We also observe the quantum interference between a single photon state and a thermal state generated in fibre. The (82±11)% visibility is obviously beyond the classical limit of 50%, showing the potential applications of the single photon source in quantum information processing.