Scientists in Basel have now succeeded in creating images of quantum dots thanks to a novel optical technology. Their development could be of interest for quantum mechanics.
As the university explains in a statement, their technology makes it possible to create images of objects that measure just fractions of a nanometre across. One nanometre is a thousand-millionth of a metre, and conventional microscopes are incapable of imaging objects of this size.
The scientists studied what are known as quantum dots, or artificial atoms in a semiconductor. They excited the atoms with a pulsed laser, which changes colour during each pulse. As a result, the atom’s fluorescence is switched on and off, thereby creating an image of it.
The technology behind their method is already well known, but the established method (Stimulated Emission Depletion or STED) only works by occupying at least four different energy levels in response to the laser excitation.
The method developed by the scientists led by Timo Kaldewey from Richard Warburton’s research team in Basel, in contrast, also works with atoms that have just two energy states. Two-state systems of this kind are important model systems for quantum mechanics.
Unlike STED microscopy, the new Basel method also releases no heat. “This is a huge advantage, as any heat released can destroy the molecules you’re examining,” said Warburton.