Landau and Lifshitz's two-volume set, "Quantum Mechanics: Non-Relativistic Theory" (Volume 3) and "Quantum Mechanics: Relativistic Theory" (Volume 4), commonly known as "The Landau-Lifshitz Course in Theoretical Physics," is a highly regarded work in the field of theoretical physics. These books cover a wide range of topics in quantum mechanics, including both non-relativistic and relativistic theories.
Volume 4 of the Landau-Lifshitz series, "Quantum Mechanics: Relativistic Theory," introduces the basics of quantum field theory and relativistic quantum mechanics. It covers topics such as quantum electrodynamics (QED), the Dirac equation, and quantization of fields. However, it should be noted that the treatment of quantum electrodynamics in this volume is relatively brief and does not delve into advanced topics.
If you are specifically interested in quantum electrodynamics, a more specialized and comprehensive text dedicated to that subject would be beneficial. One classic and highly recommended book on quantum electrodynamics is "Quantum Electrodynamics" by Richard P. Feynman. This book provides a detailed and rigorous introduction to QED and has been influential in shaping the field.
To summarize, if you are looking for a comprehensive treatment of both non-relativistic and relativistic quantum mechanics, the Landau-Lifshitz series is an excellent choice. However, if your primary focus is on quantum electrodynamics, it would be more appropriate to seek out a dedicated text on that subject, such as Feynman's "Quantum Electrodynamics."