Light-driven control of quantum materials is entering a new phase, enabled by the rapid development of high-power ultrafast lasers. In this talk, I will discuss two optical driving protocols: (i) resonant driving of collective excitations and (ii) coherent off-resonant driving.

First, as an example of resonant driving, I will show how photoexcited carriers injected into the quantum-critical magnet Sr₃Ir₂O₇ generate a nonthermal transient state, providing key clues to its elusive ground state. This transient state then relaxes into a metastable phase, pointing to optical tuning of the quantum-critical magnet.

Second, I will introduce off-resonant driving for Floquet engineering as a reversible, deterministic route to controlling quantum materials. I will propose a microscopic picture of the sub-cycle dynamics where coherent driving creates and annihilates an electronic continuum within each optical cycle. This electronic continuum can be manipulated to selectively break symmetries and couple to magnetic order in the low-frequency limit, offering an intuitive control knob for correlated quantum materials.