Shaken is different: out-of-equilibrium quantum matter

Quantum matter reveals the quantum world to the macroscopic scale in the form of intriguing phenomena that cannot be explained simply by the sum of its parts. Everyday examples include magnetism and superconductivity, captured in essence by P. W. Anderson's 1972 paper "More is different." The addition of time-dependent drives to quantum matter, such as light pulses, lifts equilibrium restrictions leading to the generalization "shaken is different," where out-of-equilibrium systems exhibit properties distinct from their equilibrium counterparts.

In this talk, we will discuss two broad applications of light-driven systems: light as a characterization tool and light as an engineering tool. First, we will discuss how the non-equilibrium conditions induced by light pulses can characterize strongly-correlated materials with high precision. As a prototypical example, we will consider magnetite, the oldest magnetic system on record. We will show how light pulses can reveal the nature of its low-temperature phase, unattainable in equilibrium. Then, we will introduce the concept of Floquet engineering, where we employ light as a powerful and flexible tool to engineer systems with designer properties. In particular, we will discuss a light-induced magnetic phase transition in bilayer chromium triiodide, a novel low-dimensional magnetic system. We will conclude with an outlook for light-controlled materials and the challenges ahead.