2025/12/29 by L Saba, L. Saba, C. D. Fosco +3
Physics and Astronomy · #Quantum Electrodynamics and Casimir Effect #Quantum and Classical Electrodynamics #Noncommutative and Quantum Gravity Theories
paper · doi:10.48550/arxiv.2512.23517
The van der Waals interaction between neutral atoms is typically studied using stationary perturbation theory for the short-distance (London) limit, while long-distance (Casimir-Polder) results are usually derived via semiclassical, time-dependent approaches. Here, we demonstrate that reformulating stationary perturbation theory calculations in terms of time-ordered correlation functions significantly simplifies the mathematical treatment. This reformulation is particularly advantageous for higher-order calculations required in the long-distance regime, where retardation effects become important. Our approach provides a unified framework connecting both limiting cases, and is intended as a bridge between advanced quantum mechanics and field-theoretic treatments of dispersion forces, suitable for graduate-level courses or specialized readers.