Parametric Instabilities of Correlated Quantum Matter

Abstract: Strongly correlated quantum materials exhibit a rich landscape of ordered phases with highly tunable properties, making them an intriguing platform for exploring non-equilibrium phenomena. A key to many of these phases is collective bosonic excitations, encoding fluctuations of the underlying order. In this work, we develop a general theoretical framework for parametric driving of such modes, whereby periodic modulation of microscopic parameters generates resonant two-boson processes. We show that the feasibility and strength of this drive depend sensitively on whether the targeted parameter alters the properties of the bosonic excitations vacuum, linking potential parametric instabilities directly to the fidelity susceptibility of the ground state. The driving facilitates nonthermal melting of the parent orders, as well as stabilization of novel steady states with experimentally distinct signatures. Through microscopic case-studies of correlated electronic systems, we identify promising driving knobs, highlight the role of quantum geometry in the collective modes susceptibility, and propose realistic experimental probes. Collective excitations are a powerful resource for steering correlated phases out of equilibrium, and will likely have several applications in quantum science. Our work provides the toolbox for controlling these excitations.