Coherent phonons in correlated quantum materials.

We briefly review a few recent progresses of the ultrafast generation and detection of coherent phonons in various types of quantum materials. Both the shared properties and unique aspects of coherent phonons are addressed, followed by concrete examples, including some recent works from our group. Perspectives on the mechanism of coherent phonons are introduced, along with experimental details, tricks, and innovations. The main focus of this review is to reveal what one can obtain from the studies of coherent phonons, thus guiding the further investigations. Particularly, we show that various interactions among different degrees of freedom can be unveiled, telling the legends of the hidden secrets in many quantum materials. The content is intended to be intriguing to non-ultrafast spectroscopy experts as well. [ABSTRACT FROM AUTHOR]