Controlling dynamics of subcycle strong-field ionization of an atom with a tricircular laser pulse

Photoelectron rescattering and interference under strong-field driving are extensively employed for microscopic structural imaging and ultrafast time-scale information extraction. Here, we propose a scheme for manipulating subcycle photoelectron dynamics using a tricircular laser field. By appropriately tailoring the intensity ratios of the three laser components, we analyze the subcycle interference of photoelectrons, such as temporal double-slit and photoelectron holographic interferences. Specifically, adjusting the fourth-harmonic component enables directional control and energy linear tunability of the rescattering electron beam. Moreover, the rescattering electron trajectory is singular without mixing from other rescattering channels within a certain intensity ratio range, which is difficult to achieve with bicircularly polarized lasers. The semiclassical calculations show agreement with full quantum simulations. The ability to produce returning electron beams with fixed incident angles and linearly controllable energy thresholds offers a powerful tool for studying ultrafast spatiotemporal dynamics in systems with complex energy-level structures and strongly oriented molecular systems.