World's Smallest Radio Constructed With Pink Diamonds

The world's smallest radio receiver has been developed by researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences. With building blocks the size of two atoms, the radio was constructed with atomic-scale defects in pink diamonds and could possibly withstand extremely harsh environments.

The research led by Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering, was published in Physical Review Applied. Loncar believes the best ways to utilize their new biocompatible technology for possible space probes or even a pacemaker for the human heart.

Using microscopic tiny imperfections in diamonds called nitrogen-vacancy (NV) centers were made by replacing one carbon atom in a diamond crystal with a nitrogen atom and remove a neighboring atom. NV centers could be used to produce single photons or identify faint magnetic fields. Information could be converted into light and make them ideal systems for quantum computing, phontonics and sensing.

A power source, a receiver, a transducer to convert the high-frequency electromagnetic signal in the air to a low-frequency current, speaker or headphones to convert the current to sound, and a tuner are the five basic radio components. In the device developed by Loncar, electrons in diamond NV centers are powered, or pumped, by green light emitted from a laser. An electromagnet creates a strong magnetic field around the diamond, which could tune the receiving frequency of the NV centers. As the NV center receives radio waves, it then converts them and emits the audio signal as red light. A common photodiode would then convert that light into a current, which is then converted to sound through a simple speaker or headphone.

Given the strength of diamonds, the radio is very resilient and could play music at 660 Fahrenheit. "Diamonds have these unique properties," said Loncar. "This radio would be able to operate in space, in harsh environments and even the human body, as diamonds are biocompatible."