Harvard scientists have developed the smallest radio receiver in the world out of the atomic-scale defects in pink diamonds. The surprising speciality of this radio is that it can function anywhere from a spacecraft to a pacemaker in heart of a human. Tiny imperfections in diamonds that are called nitrogen-vacancy (NV) centres are used by this radio to work.
In order to make NV centres, one carbon atom in a tiny diamond crystal was replaced by a nitrogen atom and a neighboring atom was also removed. This resulted in creation of a system that is essentially a nitrogen atom with a hole adjacent to it.
Single photons can be emitted or very weak magnetic fields can be detected using the NV centres, which have photoluminescent properties. It means they have the ability to convert information into light, making them powerful and promising systems for quantum computing, phontonics and sensing.
Generally, radios contains five basic components – 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.
The new radio has been created at Harvard University’s John A Paulson School of Engineering and Applied Sciences (SEAS). Green light emitted from a laser power or pump the Electrons in diamond NV centres.
These electrons are sensitive to electromagnetic fields, including the waves used in FM radio.
The NV centre converts the radio waves after receiving them and emits the audio signal as red light. That light is being converted into a current by a common photodiode. The current is then converted into sound through a simple speaker and headphone.
A strong magnetic field around the diamond is created by an electromagnet. The magnetic field can be used to change the radio station, tuning the receiving frequency of the NV centres.
Billions of NV centres were used by the researchers to boost the signal. However, the radio works with a single NV centre and emits one photon at a time, rather than a stream of light.
The inherent strength of diamond makes the radio extremely resilient. Music on the radio was successfully played at 350 degrees Celsius.
“Diamonds have these unique properties. This radio would be able to operate in space, in harsh environments and even the human body, as diamonds are iocompatible,” said Marko Loncar, professor at SEAS, who led the study.
(Video and image courtesy: Harvard)