highly charged ion clock (artwork) (IMAGE) Physikalisch-Technische Bundesanstalt (PTB) Caption Illustration of the laser interrogation of a highly charged ion clock (artwork) Credit PTB Usage Restrictions none 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.