Floquet interpretation of dynamic interference in laser-assisted photoemission

We present a theoretical study of dynamic interference (DI) in laser-assisted photoemission (LAPE), a regime widely employed in attosecond and few-femtosecond spectroscopy. Using the strong-field approximation (SFA) and a Floquet framework, we analyze the influence of a finite infrared (IR) pulse envelope under experimentally relevant conditions. In addition to the established phase modulation mechanism-referred to as laser-assisted dynamic interference (LADI)-we identify an alternative source of DI arising from a time-dependent amplitude modulation, which we term dynamic multiphoton interference (DMPI). We attribute DMPI to quantum-path interference among competing multiphoton transitions, which, depending on the exact employed parameters, can overshadow LADI when electrons are emitted along the IR polarization axis. We further delineate the conditions necessary for the clear experimental observation of both effects and assess their robustness against variations in pump pulse intensity in a realistic experimental condition.