Using the sticky tape, the team peeled a multilayer film from a transition metal dichalcogenide (TMDC) crystal and repeated the process until the material on the tape was one layer thick.
The researchers cooled this monolayer to just above absolute zero and excited it with a laser, causing the monolayer to emit single protons under specific conditions. “We were able to show that a specific type of excitement produces exactly two photons,” said Dr Christian Schneider from Julius-Maximilians-Universität Würzburg.
In a second study, the JMU scientists mounted a monolayer between two mirrors and stimulated it with a laser. The radiation excited the TMDC plate to the point where it began to emit photons itself. These were reflected back to the plate by the mirrors, where they excited atoms themselves to create new photons.
“We call this process strong coupling,” said Dr Schneider. “Light and matter hybridise, forming new quasi particles – exciton polaritons – in the process.”
In the medium term, the researchers believe this will open up interesting new applications. The ‘cloned’ photons have similar properties to laser light, but are produced in different ways; ideally, the production of new light particles will be self sustaining after initial excitation, without requiring additional energy. This, says the team, makes the new light source highly energy-efficient and suited to study certain quantum effects.