Wigner time delay in atomic photoionization

Abstract For over a century since the Nobel prize winning work by Einstein (1905 Ann. Phys. 17 132), atomic photoionization was thought to be an instantaneous process. Recent experimental advances in ultrashort laser pulse generation has allowed resolve this process time. The concept of time delay introduced Wigner (1955 Rev. 98 145–7) particle scattering appears central resolution photoionization. In review, we examine fundamental concepts time-resolved ionization processes. We will follow recent literature and show how initial disagreements between theory experiment, which persisted for nearly decade, were finally reconciled. also outline exciting prospects field driven modern computational technologies.