At the Vienna University of Technology a system of coupled
lasers has been created which exhibits truly paradoxical behaviour: An increase
in energy supply switches the lasers off, reducing the energy can switch them
on.
Sound waves fade, water waves ebb, light waves are
dissipated by a wall. The absorption of waves is a very common phenomenon. But
only recently have physicists realized that amazing new possibilities are
opened up, when this energy loss, rather than being seen as an annoying
nuisance, is actually considered a desired effect. At the Vienna University of
Technology, a system of two coupled lasers has been created, in which wave
dissipation leads to a behaviour completely contrary to intuition: additional
energy can switch it off; a reduction of energy may switch it on. This way, logical
circuits can be built using light. The experiment has now been presented in the
journal “Nature Communications”.