4 Ions Are Trapped on a Line (IMAGE) University of Copenhagen - Niels Bohr Institute Caption This is an artist's impression of the experiment. Four ions are trapped on a line. The outer Magnesium ions (green) cools the system by emitting light. Lasers are used to prepare the inner Beryllium ions (red) in an entangled state where one can not understand the state of the particles individually but have to consider the two ions as a whole. As opposed to previous experiments also the latter process happens by the emission of light. Credit (Credit NIST) Usage Restrictions (Credit NIST) 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.