Photonic quantum sources are a primary ingredient for many quantum optical experiments. However, the realization of next-generation envisaged projects such as the ground-to-satellite and or inter-satellite links for the culmination of a worldwide quantum network and real-time quantum sensing demands the development of compact and robust photonic quantum sources with high brightness and entanglement purity. Over the years, we have progressed in developing the brightest entangled photon source with enhanced tolerance based on spontaneous parametric down-conversion in second-order nonlinear optical materials. In this talk, we will discuss some of our recent results on the progress of the bright, compact single photon and entangled photon source and its use in quantum sensing based on Hong-Ou-Mandel (HOM) interference for real-time displacement measurement in nanometre scale and quantum optical tomography for temperature-dependent refractive index variation. We will also discuss the demonstration of entangled photon-based free-space quantum key distribution over 300 meters in free-space and the communication of quantum-secure text, image transmission, and quantum-assisted two-way video calling between two parties in real time.