Quantum physics finds a new application

(a) Schematic of the electro-opto-mechanical (EOM) converter in which driven microwave and optical cavities are coupled by a mechanical resonator. (b) Microwave-optical quantum illumination using EOM converters. The transmitter’s EOM converter entangles microwave and optical fields. The receiver’s EOM converter transforms the returning microwave field to the optical domain while performing a phase-conjugate operation. Credit: Shabir Barzanjeh et al./ Physical Review Letters

Quantum physics is possibly the most puzzling scientific development of the last century. If you think you understood quantum physics it probably means that you did not understand what quantum physics is (this is my paraphrasing of the famous statement of Richard Feynman: "If you think you understand quantum mechanics, it means you don't understand quantum mechanics").

For many years it has seemed that it had no practical (useful) application in everyday world. More recently scientists have discovered that part of our machinery actually exploits quantum physics phenomena (like seeing depends on quantum phenomena, the interaction of photons with rhodopsin molecules in the retina) but still the idea of applying quantum physics in some of our devices was beyond reasonability. 

The first practical application of quantum physics happened some 10 years ago in cryptography to ensure tampering proof connection. The phenomenon exploited is the one of entanglement. 

Now researchers at the University of York are proposing a new type of application of quantum physics, again exploiting entanglement.

They have discovered that entanglement hold not just at "light wavelengths", it can also apply to microwave radiation. By generating two beams at different wavelength (see the figure) one in the optical spectrum the other in the microwave spectrum and correlating one another they are able to detect objects that previously were undetectable to radar systems. This applies to detect "stealth" place (which doesn't look like a life changing result) as well as detecting single molecules. The detection of these molecules is tricky since there is a lot of noise in the signals bouncing back from the cells and identifying the specific variation introduced by a specific molecules is basically impossibile.

Not so with the application of quantum physics and the use of entanglement. This result in a detection system using very low power (hence able to hit single molecules) with very high sensitivity (hence able to detect the presence of a specific protein, as an example). Since cancer cells have specific proteins that you won't find in normal cells this system would allow the detection of cancer in a much better way than a radiography or MRI but with the same low invasiveness (and this would be a life changing discovery).

Amazing how something as theoretical (and abstruse) as quantum physics may end up in everyday tools! 

Author - Roberto Saracco

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