First photo of atom's shadow

(Nanowerk News) A pixelated image of a black spot on an orange background isn't likely to win any photographic competitions.
But the seemingly bland image, taken by scientists at Queensland's Griffith University, could potentially revolutionise mankind's understanding of physics and how the world works.
A research team at the university's centre for quantum dynamics in Brisbane has been able to photograph the shadow of a single atom for the first time (see paper in Nature Communications: "Absorption imaging of a single atom").
Artist's illustration of a single atom shadow
Artist's illustration of a single atom shadow. (Image: Kielpinski group, Griffith University)
Professor Dave Kielpinski says the image is at the extreme limit of microscopy.
"You cannot see anything smaller than an atom using visible light," Prof Kielpinski said in a statement.
"We wanted to investigate how few atoms are required to cast a shadow, and we proved it takes just one."
The scientists used a super high-resolution microscope not available anywhere else in the world.
A single atom of the element ytterbium was held by electrical forces and exposed to a specific frequency of light, which caused it to cast a shadow that could be photographed.
Research team member Erik Streed said the photo had myriad implications, including revolutionising quantum computing and biomicroscopy.
"Because we are able to predict how dark a single atom should be, as in how much light it should absorb in forming a shadow, we can measure if the microscope is achieving the maximum contrast allowed by physics," Dr Streed said.
"This is important if you want to look at very small and fragile biological samples such as DNA strands where exposure to too much UV light or x-rays will harm the material."
Source: Griffith University
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