This two-volume set CCIS 2743 and 2744 constitutes the refereed proceedings of the 1st International Conference on Quantum Engineering Sciences and Technologies for Industry and Services, QUEST-IS 2025, held in Paris, France, during December 1&4, 2025.

The 68 full papers included in this book were carefully reviewed and selected from 120 submissions. They were organized in topical sections as follows: 

Part I: Enabling Technologies; Quantum Sensors Applications; Quantum Sensors in Detection and Sensing; Quantum Communications & Test Platforms for Qkd; Quantum Key Distribution; Towards A Quantum Internet Infrastructure; Quantum Algorithms, Computing & Simulation & Benchmarking: Methods & Applications; Error Mitigation & Fidelity; and Quantum Algorithms for Finance & Industry.

Part II: Quantum Algorithms, Computing & Simulation & Quantum Algorithms for Finance & Industry; Scheduling, Logistics & Complex Systems; Quantum Machine Learning; Physics & Engineering Applications; Simulation & Quantum Chemistry; Hardware & Architectures; and Specialized Applications & Security.