Figure 1 (IMAGE) Institute for Basic Science Caption Graphic of the system: a two-dimensional superconductor close to its critical temperature. The system is exposed to electromagnetic field (orange arrow) with THz frequency. Stripes of metals as a grating (not shown) are required for the excitation of plasmons, a special type of excitations of unbound electrons in the superconductor. Thus, unbound electrons act as mediators: they interact with each other, with light (as plasmons), and with the Cooper pairs, depicted as dashed red circles. Credit IBS Usage Restrictions Please indicate the credit. 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.