Dynamic interference of photoelectrons produced in below-threshold ionization

We study the temporal interference of photoelectrons emitted during the rising and falling edges of intense femtosecond laser pulses, that can ionize atoms via near-resonant transitions. Due to the near-resonant coupling with the laser pulse, the emerging atomic dressed states repel each other, giving rise to the Rabi splitting that is primarily controlled by the laser intensity and detuning. Our numerical and analytical analysis reveals that dynamic interference is observed when the Rabi splitting of the dressed states is maximized while the ionization of the atom remains small (Phys. Rev. A 108, L061101, 2023). We demonstrate that these two conditions are fulfilled when the atom is driven off-resonantly within the one-Rabi-cycle regime at perturbative laser intensities. As a result, the single peak of the photoelectron spectrum found in the weak-field limit is replaced by a pronounced multipeak pattern.