A team of researchers from Harvard John A. Paulson School of Engineering and Applied Sciences recently came up with the smallest radio receiver in the world. The receiver has been carved out of an arrangement of atomic scale-defects present in pink diamonds. It is a very small radio that has two atoms thick building blocks, and the best part, it is completely biocompatible and capable of facing harshest environmental conditions, therefore, you can use it anywhere right from a space probe to a chip in human body. The research was led by a Tiantsai Lin Professor of Electrical Engineering at SEAS along with his graduate student Limbo Shao.
The radio makes use of some very small imperfections in the diamonds that are known as nitrogen-vacancy centers. In order to make NV centers, the researchers replace a single carbon atom in single diamond crystal with one nitrogen atom and remove the nearby atom leading to creation of system that definitely has a nitrogen atom with a hole right next to it. NV centers can also be engaged emit single photons or find the weakest magnetic fields. They have numerous photoluminescent properties which means these can convert any information into light which makes them very powerful and promising frameworks for sensing, photonics, and quantum computing.
Radios have have five fundamental constituents that include a receiver, a transducer that convert the high-frequency electromagnetic signal present in air into a low-frequency current, a power source, headphones or speakers that convert current into a tuner and sound. In the Harvard made instrument, the electrons present in diamond NV centers get pumped or powered through green light emitted from laser.
These electrons are quite sensitive to electromagnetic fields that also include the waves used in FM radios. For instance, when NV center receives radio waves, it turns those into audio signal and emits those as red light. A regular photodiode is capable of converting light into current that then gets converted into sound via a simple headphone or speaker. The electromagnet forms a very intense magnetic field near the diamond that can then be used for switching radio stations or tuning the receiving frequency of those NV centers. The team here used over one billion NV centers for boosting signals, however, the radio works well with a single NV center emitting a single photon in one go. It is an extremely robust system that has inherited the diamond’s strength.
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