This volume presents the Book of Abstracts for CEQPAS 2025 conference, held in Belgrade, Serbia, from 3–5 November 2025, in celebration of the International Year of Quantum Science and Technology (IYQ). The conference marked the centennial of quantum theory and brought together researchers in quantum physics and chemistry, atomic and molecular spectroscopy, plasma science, and related fields. Contributions span experimental and theoretical advances, including applications of artificial intelligence and machine learning in quantum research. CEQPAS contributions were organised in five interlinked sessions: 1. Atomic and molecular spectroscopy and its applications to atmospheric sciences and astronomy; 2. Collisions and their applications in plasma physics;3. Studies in Chemical physics & physical chemistry; 4. The application of quantum science to our wider understanding of phenomena including radiation sciences; 5.The use of Artificial Intelligence (AI) and Machine Learning (ML) for atomic and molecular data analysis and generation. The volume also introduces the MOLecular Excited State spectroscopy (MOLESs) Consortium, dedicated to revisiting and expanding the foundational knowledge of molecular electronic spectroscopy.