Copper mirrors direct and focus microwave photons in electrons on liquid helium system. The focusing mirror (on the left) is made by pressing a hard stainless steel ball (also shown in the picture) into a soft piece of copper. The flat mirror (on the right) shows two concentric circular electrodes (aka a Corbino pair) that are used to measure electron conductivity.
(Picture: Olga Garnova / CC BY-SA 2.0)
4/4 Back to the Article