在參量降頻轉換這個過程中，準相位匹配是一項很重要的機制之一，然而在現今眾多的實驗與理論中，並沒有明確地指出當在晶體週期性極化的過程中，這些製程上的誤差會對於產生出的光子對它們的量子特性有何影響。
因此，在本篇論文中，我們將深入探討這些誤差所帶來的非理想性與隨機性的準相位匹配，想知道對於這些產生出的糾纏光子對會有何種效應，因此，我們在實驗中量測了糾纏光子對的光譜分佈， 並且提出了一套理論模型解釋我們所觀察到的現象，最後也對於這些光子對，進行了量子力學特性上的量測，如反關聯性參數(α_2d)以及Franson-type干涉。此外，本論文內容以發表於Scientific Reports 6,26079(2016)

Quasi-phase-matching (QPM) has enriched the capacity of parametric down-conversion (PDC) in generating biphotons for many fundamental tests and advanced applications. However, it is not clear how the non-idealities and randomness in the QPM grating of a parametric down-converter may affect the quantum properties of the biphotons. This thesis intends to provide insights into the interplay between PDC and non-ideal or random QPM structures. Using a periodically poled nonlinear crystal with short periodicity, we conduct experimental and theoretical studies of PDC subject to non-ideal duty cycle and random errors in domain lengths. The work described in this thesis has been published in Scientific Reports 6, 26079 (2016)

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