Fonte de pares de fótons quanticamente correlacionados gerados por conversão paramétrica descendente espontânea com cristal PPKTP bombeado por um laser de diodo de baixo custo

Abstract

The rapid growth of the quantum technologies industry has propelled intelligent solutions for cost reduction in scientific research. A commonly employed strategy involves the use of diode lasers for the pumping process in sources based on spontaneous parametric downconversion. This is justified by the fact that, when compared to conventional lasers, diode lasers demonstrate significant cost-effectiveness advantages. In this context, a homemade control system was utilized for the diode laser, aiming to present an economically viable alternative. In this dissertation, we undertook the construction of the current controller for a diode laser and its characterization. The objective is to use this laser in the generation of photon pairs with quantum correlations through the process of spontaneous parametric down-conversion, occurring in nonlinear crystals. In this dissertation, we employed a PPKTP crystal with type II phase matching, where the pairs are generated collinearly to the pump beam. Using the Cauchy-Schwarz inequality, expressed in terms of the parameter R, where for R > 1 non-classical effects are observed, we measured the violations of this inequality during the conducted experiments. We obtained a maximum value of R = 65 ±22, highlighting the violation of the inequality and validating the successful construction of the correlated photon source using a diode laser for pumping.