Designing adiabatic time evolution from high-frequency bichromatic sources

Abstract

We investigate the quantum dynamics of a two-level system driven by a bichromatic field, using a nonperturbative analysis. We make special emphasis in the case of two large frequencies, where the Magnus expansion can fail, and in the case of a large and a small frequency, where resonances can dominate. In the first case, we show that two large frequencies can be combined to produce an effective adiabatic evolution. In the second case, we show that high-frequency terms (which naturally arise as corrections to the adiabatic evolution obtained in the first case) can be used to produce a highly tunable adiabatic evolution over the whole Bloch sphere, controlled by multiphoton resonances.