We present a new method for the spectral characterization of pulsed twin beam sources in the high gain regime, using cascaded stimulated emission. We show an implementation of this method for a ppKTP spontaneous parametric down-conversion source generating up to 60 photon pairs per pulse, and demonstrate excellent agreement between our experiments and our theory. This work enables the complete and accurate experimental characterization of high gain effects in parametric down conversion, including self and cross-phase modulation. Moreover, our theory allows the exploration of designs with the goal of improving the specifications of twin beam sources for application in quantum information, computation, sampling, and metrology.

中文翻译：

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使用级联受激发射来了解高增益双光束源

我们提出了一种新的方法，用于级联受激发射的高增益状态下的脉冲双光束源的光谱表征。我们为ppKTP自发参量下转换源展示了该方法的实现，每个脉冲可生成多达60个光子对，并证明了我们的实验与理论之间的出色一致性。这项工作可以对参数下变频中的高增益效应（包括自相位调制和交叉相位调制）进行完整，准确的实验表征。此外，我们的理论允许探索设计，目的是提高双束源的规格，以用于量子信息，计算，采样和计量。