An Atomic Scale Radio Tuner

Although it pains me to say it, researchers at Harvard have created a radio tuner by replacing and/or removing atoms in a diamond crystal:

The radio uses tiny imperfections in diamonds called nitrogen-vacancy (NV) centers. To make NV centers, researchers replace one carbon atom in a diamond crystal with a nitrogen atom and remove a neighboring atom—creating a system that is essentially a nitrogen atom with a hole next to it. NV centers can be used to emit single photons or detect very weak magnetic fields. They have photoluminescent properties, meaning they can convert information into light, making them powerful and promising systems for quantum computing, photonics and sensing.

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In the Harvard device, electrons in diamond NV centers are powered, or pumped, by green light emitted from a laser. These electrons are sensitive to electromagnetic fields, including the waves used in FM radio, for example. When NV center receives radio waves it converts them and emits the audio signal as red light. A common photodiode converts that light into a current, which is then converted to sound through a simple speaker or headphone.

 So, there are macro scale components that read the audio signal and amplify it so that it can be heard and also handle tuning, but if you've ever seen those old console model radios that were basically furniture, then you know how far we've come.

Sometimes you just have to shake your head in wonder. 

Read more at: World's smallest radio receiver has building blocks the size of two atoms