(IMAGE) Yokohama National University Caption Schematics of the ultrafast broadband terahertz excitation and polarization rotation detection of phonon in WSe2. Obtained result (lower right) includes the coherent phonon oscillation signal excited via sum-frequency process (upper right). Credit Satoshi Kusaba / Yokohama National University Usage Restrictions The image may only be used with appropriate caption or credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.