Interaction picture

Summary

The interaction picture is a description of quantum dynamics between the Schrödinger picture and the Heisenberg picture. The Hamiltonian is split as $H = H_0 + V$, where $H_0$ is a simple part with known dynamics and $V$ is the interaction. Observables evolve with $H_0$, and state vectors evolve only under the effect of $V$. It is the starting point of time-dependent perturbation theory and of the Dyson series in quantum field theory.