Adarsh Ganesan

A short laser pulse hits a crystal, and instead of a single sound, the crystal responds with a whole ladder of frequencies, each separated by the same interval. This is how a phononic frequency comb is born, a phenomenon that physicists are exploring in a material with an unusual internal structure.

Quartz microbalances are thin plates that vibrate at a frequency of five million times per second. When a drop of liquid lands on the plate, the vibration changes: from these changes, you can determine the drop's mass and its elasticity.