R. G. Herb Condensed Matter Seminars |
Events on Thursday, September 10th, 2026
- Shaping Quantum Materials with Light
- Time: 10:00 am - 11:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Daniel Kaplan, Rutgers
- Abstract: The richness of phases in quantum materials can be greatly augmented by light-matter interaction. I will present new theories of light-matter interaction in, which generate new phases in 2D and correlated solids that are inaccessible in equilibrium. To begin, I will show that sliding ferroelectricity in 2D bilayers can be driven by using light to reshape the free energy of the bilayer stack. Employing time-dependent self-consistent density functional theory, I will connect this idea to quantum geometry; light couples at quadratic order to charge fluctuations, which play a dominant role in interlayer bonding interactions of van der Waals materials. Beyond a critical threshold in light intensity — set by the energy barrier between two stackings — layers will slide against each other. I will use this to introduce the concept of an opto-mechanical transistor, with direct application to MoSe2. Next, I will show that in strongly correlated systems, such as in charge density waves, parametric coupling between amplitude and phase modes produces spatiotemporal patterns that twist and wind the phase mode in space and time. I will discuss the origins of this phenomenon, tracing it back from spontaneous symmetry breaking in quantum materials, to how light-matter interaction in dynamically generates a coupling between modes which are de-coupled in equilibrium (and do not interact with light). I will discuss implications of this idea broadly, demonstrating the power of parametric coupling in solids (in phonons, and beyond). To conclude, I will show how light-matter interaction can drive topological transitions in the recently discovered stacking-tuned Z_2 material BiSb. By coupling to phonons which control the degree of band inversion in this system, I will present a practical example of light-driven topological phase transitions. These theories present a new approach to tuning quantum materials and allow for exploring the vast landscape of quantum phenomena lying out of reach in equilibrium.
- Host: Elio König