Schematic Representation (IMAGE) Physikalisch-Technische Bundesanstalt (PTB) Caption Measuring the influence of thermal ambient radiation on the frequency of the trapped ion: the "clock laser" (blue beam) excites the trapped ion (yellow) with a special pulse sequence. The resonance frequency of the ion is influenced by infrared radiation (here by an infrared laser, red beam). This can be measured by means of the clock laser. Credit (Fig.: PTB) Usage Restrictions None License Licensed 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.