Omshankar2025-11-182025-05-30https://ir.iitd.ac.in/handle/123456789/7762enPhase matching techniques for SPDCTwo- photon interference visibilityPolarization-entangled photonsSpontaneous parametric down-conversionSecond-harmonic generationSpatial light modulatorRobust entangled-photon sources based on ppKTP for rotational-misalignment-resilient free-space QKDThesis