High harmonic generation in solids and quantum materials.

A laser pulse fired into a crystal of magnesium oxide can generate bursts of ultraviolet light at frequencies far beyond the original beam. This project asks why certain solids produce these high harmonics—and which physical mechanisms are responsible. In the low-harmonic regime, the key question is whether the light comes from so-called Brunel harmonics, the Kerr effect, or injected charge carriers. The researcher will test this in common crystals such as MgO and quartz. A second strand examines the same process in melamine cyanuric acid, a crystalline complex whose honeycomb structure resembles graphene but contains hydrogen, nitrogen, and oxygen instead of carbon. Finally, the work compares these results with high harmonic generation in graphene and Weyl semimetals. This is fundamental science. There is no immediate practical application. But high harmonic generation in gases already underpins attosecond physics—the ability to watch electrons move in real time. Understanding how the same process works in solids could eventually lead to compact, solid-state sources of extreme ultraviolet light for imaging, spectroscopy, or future electronics. For now, the goal is simply to map the electron dynamics in these materials and settle a debate about what is actually happening inside them.