Emergent collective excitations in semiconducting moire superlattices

Exotic collective excitations are the hallmarks of emergent quantum states and may enable fundamentally new device concepts. Semiconducting moire superlattices recently emerged as an attractive platform for engineering many-body states. Experimental access to collective excitations, however, has remained challenging as they often carry quantum numbers other than charge and therefore difficult to couple to. In this talk, I will discuss our recent efforts to investigate emergent low-energy excitations in semiconducting moire superlattices, including excitons, magnons, etc. Using an ultrafast wide-field imaging technique, we record their complete space-time evolution, such as space-and-time-resolved transport. This allows us to simultaneously capture and separate multiple coexisting excitations, identify their nature and distinguish them from single-particle excitations, which have been difficult from steady-state measurements. Our results highlight new insights encoded in collective excitations and open avenues for studying and engineering correlated quantum systems through nonequilibrium approaches.