"Quantum technologies offer new quality with respect to classical ones by enhancing sensitivity of measurements and offering unconditional security of information transfer. Their optical implementation within the current technology is limited by inefficient detection and use of single photons. The solution is to apply macroscopically populated quantum states of light (MQSL) created by quantum cloning. However, they suffer from low distinguishability. The aim of this project is to merge unique properties of these hybrid states with innovative filtering and detection methods for applications in quantum technologies. The new concept is to use a filter relying on a conditional weak measurement described by a positive operator valued measure. It preserves quantum coherences and entanglement. Also new detection techniques genuine to continuous variables will be tested. Existing sources of MQSL will be improved by quantum state engineering, broadening palette of the experimentally accessible non-Gaussian states. Genuine macroscopic entanglement and multi-mode Bell tests, possibly with preselection technique, will be demonstrated. Feasible entanglement witnesses and measures will be proposed. They will help testing MQSL for quantum information, cryptography, metrology, teleportation and entanglement distillation protocols. Coupling between MQSL and polaritonic Bose-Einstein condensate, also a macroscopic superposition of light, and biomolecules will be examined towards quantum memories. Decoherence effects will be included in all steps of the analysis. Additionally, conclusions about the fundamental aspects of quantum mechanics are expected: testing it against local hidden variable models and the quantum-to-classical transition. Methodology includes analytical and numerical computations within the framework of quantum optical methods and tools. This project supports the applicant in building her own group, completing habilitaion degree and home country career integration."