Entangled Rainbows Generated By Spontaneous Parametric Conversion

Broadband tunable and multipartite entanglements are essential for further developments of quantum information applications, such as quantum network, atomic memory, and photonic interface of quantum bits. Though most highly entangled photon pairs have been generated by means of parametric down-conversion, it is difficult for parametric up-conversion process to implement the broadband tune ability or extend to short wavelength with the one nonlinear crystal or pump source, as parametric up-conversion has been thus far limited in experiments.This dissertation provides our experimental investigations for simultaneous spontaneous parametric up conversion and down conversion to generate time-bin entangled rainbows tunable in the ultraviolet and visible regions. Our research work can be summarized as followings.1. The generation of colored conical emission from modulation instability (MI) during nonlinear optical parametric process in quadratic media. This part includes the spatiotemporal MIs by means of second harmonic (SH) generation, quadratic nonlinear coupling between fundamental and SH fields, as well as the degenerate parametric light scattering.2. The generation of tunable correlated rainbow pairs, which results from some cascade non-collinear optical parametric amplification (NOPA) in a quadratic medium seeded with a continuous-wave (cw) and pumped with pulsed-wave. The correlated spontaneous up conversion and down conversion photons exhibits a high beam brightness, small spatial divergence, and broad spectral tunability. Such processes could be controlled by continuous-wave light beams for the all-optical control of highly correlated pairs of energetic photons.3. First observation of a continuously select multi-wavelength entangled photon pairs based on rainbow pairs in NOPA in the ultraviolet and visible regions. The multi-wavelength entangled photon pairs are formed and characterized with an interferometer with a fixed optical path length difference between its short and long arms. The pumping intensity shall be low enough to ensure negligible generation rate of more than one photon pairs so that the ultraviolet and visiblephoton pairs are concurrently generated at one of the two well-defined times.