Defects aren't always well-received things in scientific studies. But by causing a deliberate defect in pink diamond crystals, Harvard University researcher have created what they're calling the world's smallest radio. It measures only two atoms in size and is robust enough to withstand the tortures of alien planets or the rough-and-tumble environment inside our own bodies.
The defect in question is called a nitrogen-vacancy center and is created when two carbon atoms are removed from a diamond, one is replaced with a nitrogen atom, and the other is left empty. Such a system can detect weak magnetic fields (such as those used in radio transmissions), emit light or convert information into light. Using these qualities, the Harvard team made their radio.
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To get the broadcast going, the NV center is first powered up with a beam of green laser light that activates the electrons swirling around the nitrogen atom. After that, when radio waves hit the system, it converts them to red light. That red light is turned into a current through the use of a semiconductor known as a photodiode. When that current is fed through speakers, sound is produced. Different stations can be tuned in through the use of an electromagnet that creates a field surrounding the device.
In their test, the team used billions of NV centers to amplify the radio signal, although they say it can work with just one center, measuring the size of two atoms.
Because the radio is embedded in diamond – a famously tough material – it can withstand harsh conditions, meaning it could one day be used in outer space or perhaps inside our own bodies for diagnostic purposes. In their testing, the Harvard researchers were able to play music at 350° C (about 660° F).
Their work has been published in the Physical Review Applied journal and you can see a demonstration of the radio spreading some holiday cheer in the video below.