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The magic of “Phonons”

You know a lot about Photons, quantum of light, but may be you haven’t explored the intriguing "Phonons". These are "quantum of sound" (I am using quantum in a very loose way).
Researchers at the Lawrence Berkeley Laboratory have manage to create phonons by using laser pulses to hit gold plasmonic nano structures that as result vibrates generating phonons at a frequency of 10GHz. Not a sound you are likely to perceive…. Interesting way of converting light into sound!
Notice that phonons are not a manifestation of an electromagnetic field, they require a medium to propagate (like air or body tissue). This is an advantage if you are considering using waves to look at body parts. Whereas the electromagnetic field of light will be absorbed by tissue (and hence blocked at its surface) sound waves can penetrate in the tissue and this is why sound is used for diagnostic imaging.
The higher the frequency of sound waves the better the resolution. Present "echography" uses sounds waves at 20MHz. By increasing this frequency to 20GHz you get much better resolution.
Sound waves can also be used to inspect materials, like checking the integrity of an airplane wing.
The biggest challenges the researchers faced were how to generate the sound pulses and how to direct them. According to the one of the researchers, Kevin O’Brien:
“Through the interplay between phonons and localized surface plasmons, we can detect the spatial properties of complex phonon modes below the optical wavelength. This allows us to detect complex nanomechanical dynamics using polarization-resolved transient absorption spectroscopy.”
It may leave you confused, but it shows that there is a good deal of science and technology behind this. In lay man terms they have found a way to generate extremely high frequency sound pulses and at the same time a way to detect the reflection of these pulses (similarly to what happens in the radar where reflected waves are compared to the ones sent and their difference can be processed to identify objects and their structure).

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. He's currently the Chair of the Symbiotic Autonomous Systems Initiative of IEEE-FDC. Until April 2017 he led the EIT Digital Italian Node and up to September 2018 he was the Head of the EIT Digital Industrial Doctoral School. Previously, up to December 2011, he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the Industry Advisory Board within the Future Directions Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books. He writes a daily blog,  http://sites.ieee.org/futuredirections/category/blog/, with commentary on innovation in various technology and market areas.