314 research outputs found
CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer
A polarization entangled photon pair source is widely used in many quantum
information processing applications such as teleportation, quantum swapping,
quantum computation and high precision quantum metrology. Here, we report on
the generation of a continuous-wave pumped degenerated 1550 nm polarization
entangled photon pair source at telecom wavelength using a type-II
phase-matched periodically poled KTiOPO4 crystal in a Sagnac interferometer.
Hong-Ou-Mandel-type interference measurement shows the photon bandwidth of 2.4
nm. High quality of entanglement is verified by various kinds of measurements,
for example two-photon interference fringes, Bell inequality and quantum states
tomography. The wavelength of photons can be tuned over a broad range by
changing the temperature of crystal or pump power without losing the quality of
entanglement. This source will be useful for building up long-distance quantum
networks
Generation and Manipulation of Nonclassical Photon Sources in Nonlinear Processes
Nonclassical photon sources are key components in quantum information science and technology. Here, the basic principles and progresses for single photon generation and their further manipulation based on second- or third-order nonlinear processes in various degrees of freedom are briefly reviewed and discussed. Based on spontaneous parametric down-conversion and spontaneous four-wave mixing, various nonlinear materials such as quasi-phase-matching crystals, dispersion-shifted fibers, and silicon-on-insulator waveguides are used for single photon generation. The kinds of entanglement generated include polarization, time-energy, time-bin, and orbital angular momentum. The key ingredient for photon pair generation in nonlinear processes is described and discussed. Besides, we also introduce quantum frequency conversion for converting a single photon from one wavelength to another wavelength, while keeping its quantum properties unchanged. Finally, we give a comprehensive conclusion and discussion about future perspectives for single photon generation and manipulation in nonlinear processes. This chapter will provide an overview about the status, current challenge, and future perspectives about single photon generation and processing in nonlinear processes
Efficient infrared upconversion via a ladder-type atomic configuration
We have demonstrated experimentally that infrared light at 1529.4nm can be
converted into the visible at 780nm with 54% efficiency through a ladder-type
atomic configuration in 85Rb. Specifically we theoretically analyze that high
efficiency is due to the large nonlinear dispersion of the index of refraction
from the off-resonant enhancement in a four-wave mixing (FWM) process. By using
two perpendicular polarized pump fields, the coherence of two FWM processes in
this configuration is verified.Comment: The new version is published in Journal of Modern Optic
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