Role of multilevel Landau-Zener interference in extreme harmonic generation

Motivated by the observation of multiphoton electric dipole spin-resonance processes in InAs nanowires, we study theoretically the transport dynamics of a periodically driven five-level system, modeling the level structure of a two-electron double quantum dot. We show that the observed multiphoton resonances, which are dominant near interdot charge transitions, are due to multilevel Landau-Zener-Stückelberg-Majorana interference. Here, a third energy level serves as a shuttle that transfers population between the two resonant spin states. By numerically integrating the master equation, we replicate the main features observed in the experiments: multiphoton resonances (as large as eight photons), a robust odd-even dependence, and oscillations in the electric dipole spin-resonance signal as a function of energy-level detuning.