The first scanner based on the laws of quantum physics is ready, capable of penetrating through skin, paper and fabrics to detect the presence of explosives, but it can also be used for quality controls and for the diagnosis of skin diseases. Described in the journal Advanced Materials, it is the result of an international collaboration led by physicists Antonio Politano of the University of L’Aquila and Lin Wang of the Chinese Academy of Sciences in Shanghai.
The technology behind the new scanners is based on a new generation of photodetectors that operate in the Terahertz wavelength, the region of the electromagnetic spectrum that lies between microwave and infrared frequencies and is of great interest for in the fields of diagnostic imaging, body scanners for airport security and high-speed wireless communication. Millions of times lower in frequency than X-rays, Terahertz waves don’t have enough energy to cause damage to cells’ DNA. Photodetectors convert Terahertz light waves into electrical signals that can be easily detected and analyzed.
Another novelty is that they use materials with quantum properties, called “topological semimetals”, such as cobalt ditelluride, which have electrons that can reach speeds close to that of light and are much more efficient in combining different functions than the materials used so far. In fact, they are able to absorb Terahertz radiation, emit electrons and generate an electric current proportional to the incident radiation. “These properties are hard to find in a single material, which makes creating an efficient Terahertz photodetector a very complex process,” Politano notes.
“The prototype is based on an innovative quantum phenomenon that occurs in topological semimetals, called the ‘nonlinear Hall effect’, which implies a deviation of their conduction electrons in the presence of a magnetic field, but with different characteristics compared to the Hall effect commonly observed in the case of semiconductors or metals”, says Politano. In the case of the nonlinear Hall effect, the deviation is not proportional to the increase in the magnetic field. “Thanks to these results – he concludes – the era of innovative body scanners based on the quantum properties of materials has just begun, with technological prospects of enormous social and economic impact”.
Source: Ansa
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