Title: Light-induced phase transitions in complex matter

Abstract: Phase transitions are a fundamental aspect of physics and chemistry. The common ones, such as boiling or freezing of water, are encountered early in life, and are a staple of early childhood education. But beyond these basic ones, in materials physics a whole host of transitions into unusual phases can occur, and much of modern condensed matter physics is concerned with the understanding and control of these phases. The typical “control knobs” may be electric/magnetic fields, pressure, temperature, or chemical composition. Based on these “knobs”, elaborate phase diagrams with complex, intertwined phases are constructed. Recently, a new type of control knob has been realized — ultrafast laser pulses that may push the material out of its equilibrium phase diagram and into a new one. This new capability comes at a price: complex materials are already difficult to understand in equilibrium, so understanding what happens when you drive them away from this state requires new tools and a new language. In our group, we have been at the forefront of developing these, and have built a ground-up understanding of many-body systems driven out of equilibrium. In this talk, I will briefly introduce equilibrium phases of complex matter, and then discuss what light-induced phases of complex matter are, how they may be realized, and how we can use these techniques to further our understanding of condensed matter physics of materials.