Topological insulators conduct electricity on their surfaces but not through their interiors. SLAC scientists discovered that high harmonic generation produces a unique signature from the topological surface.

This is the first direct observation of a hydroxyl-hydronium complex – important for a wide range of chemical and biological processes from the tails of comets to cancer treatment.

This new understanding could aid the development of more efficient clean energy sources.

Just as pressing a guitar string produces a higher pitch, sending laser light through a material can shift it to higher energies and higher frequencies. Now scientists have discovered how to use this phenomenon to explore quantum materials in a new and much more detailed way.