The main problem in many-body phenomena is the multitude of competing factors making it hard to pinpoint the most relevant ones. Our approach to tackle this problem by using the versatile toolbox of nonlinear optics.

One way is to selectively perturb the individual degrees of freedom in a quantum material on a timescale so fast that parts of the system don’t have time to react. Observing the response of the material in this narrow time window (a few picoseconds or less) can often be useful to identify the microscopic mechanisms behind complex phenomena.

A complementary approach is to subject the material to extreme fields comparable to those that hold the system together and use the response to expose the intrinsic phenomena within the system that normally remain hidden in the linear response regime.

We are currently using these techniques to investigate quantum spin liquids, “Planckian” transport in correlated systems and optoelectronic properties of lead-halide perovskites among other things.