Sub-cycle Control of Optical Response by Using a Terahertz Excitonic Dressed State

The nonlinear light-matter interaction lies at the heart of controlling the electronic systems for the purpose of developing ultrafast optical switching and modulation devices [1], and attosecond laser technology [2]. In general, the interaction causes the formation of photon dressed state that is a quantum superposition state with energetically spaced sidebands and enables to generate the phase-locked sideband polarizations leading to unique optical responses. However, so far, the study is limited to the driving-cycle-averaged optical experiments [3, 4], and thus, our understanding of the role of quantum phases in the optical response and their potential for electro-optic devices remains limited.