Understanding emergent quantum phenomena in the real world

Abstract: With the advancements in quantum materials research, the emergent quantum many-body phenomena, such as competing orders, topological order and fractionalization, can be realized in much more controllable ways.

However, resolving them experimentally can be challenging. In this talk, I will tell two stories of understanding the emergent phenomena in quantum materials, with setups both in and out of equilibrium. First, I will discuss our theory of the charge orders in recently extensively studied Vanadium based kagomé metals, which show a cascade of phase transitions as temperature lowers, from charge order, potential time reversal symmetry breaking order to superconductivity. The constraints on the theory space from various experiments will be elaborated. Next, I will propose the use of ultrafast pump-probe setup to study the time-domain dynamics of (quasi) long range order in two dimensional magnets, which in the meantime can reveal the interactions between low and high energy states of the system. I will conclude with an outlook on further developing these ideas towards probing and controlling other exotic quantum many-body states.