Chapter 1.Introduction -- Chapter 2.Background -- Chapter 3.Non-classical states of light after strong-laser field processes in atoms -- Chapter 4.Non-classical states of light after high-harmonic generation in molecular and solid systems -- Chapter 5.Non-classical states of light for Device-Independent Quantum Key Distribution -- Chapter 6.Conclusions -- Chapter 7.Additional material of Chapter 2 -- Chapter 8.Additional material of Chapter 3 -- Chapter 9.Additional material of Chapter 4 -- Chapter 10.Additional material of Chapter 5.

This doctoral thesis has a dual focus. Firstly, it studies the generation of non-classical states of light through strong-field processes, where light-matter interactions involve light intensities contending with the forces binding electrons to their nuclei. This exploration demonstrates the utility of strong-field phenomena in generating non-classical states of light, with properties dependent on specific dynamics and materials involved in the excitation. Secondly, it investigates the constraints and prerequisites of non-classical light sources—beyond those studied in the first part—for advancing quantum communication applications,specifically in quantum key distribution. The aim here is to create a secret key exclusively known by the communicating parties for encrypting and decrypting messages. As a whole, this work serves as a foundational step towards leveraging strong-field physics as a prospective tool for quantum information science applications, as well as displaying the advantages and limitations of photonic-based setups for quantum key distribution. With its very clear style of presentation, the book is an essential reference for future researchers working in this field.