Harvard researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have built the world’s smallest radio receiver, made out of atomic scale defects in pink diamonds. The tiny radio is robust and biocompatible, which means it can be used in all sorts of extreme applications, from a space probe headed to Venus to a pacemaker embedded in a human body.
The radio is based on nitrogen vacancy centres, with one carbon atom placed in a tiny diamond with a nitrogen atom and removing the neighbouring atom. The nitrogen vacancy centres are then powered by a green laser. The electrons in the nitrogen vacancy centre are sensitive to electromagnetic waves, including FM signals. When the electrons in a nitrogen vacancy centre receive radio waves, they convert the radio waves and emit streams of red light. This red light stream can be interpreted with a photodiode, that converts the stream of light into a current, which can be converted to sound and heard on conventional speakers.
An electromagnet placed around the diamond can be used to tune in to a particular radio station. Billions of nitrogen vacancy centers can be used to boost the signal, but the radio works even with a single nitrogen vacancy center, emitting one photon at a time. The nitrogen vacancy centers can convert information into light, which potentially allows such tiny structures to be used in photonics, sensors and quantum computers.