Scientists Achieve Movement of Quantum Dots through Sound Waves

A research team from the Ruhr Universitat Bochum have collaborated with researchers at Grenoble and Tokyo to devise a new method to align electrons differently in order to distinguish between each electron and control their movement through sound waves.

Generally, electrons are identical in nature and are available in less density in semi conductors. In other words the distance between each electron is more in semi-conductors than in metals.

In this study a quantum dot was identified between four electrodes in order to create an object with zero-dimension containing many electrons. Radio frequency voltage is then applied along the surface of the semiconductor. To create a sound wave, researchers used the reverse process of a piezo ignition system in which a crystal is deformed to create a voltage. Here they deformed the crystal by applying voltage and created a sound wave. With the help of this sound wave the electron was moved across a channel to reach a quantum dot located at a distance of .4 µm. The same mechanism was applied to move the electron back again to its starting point.

Since electrons are all identical and difficult to distinguish, scientists have come up with ways to align each electron differently based on the spin of the electron. The spin time of the electron is longer than the time it takes to travel through the channel. Hence the electron can arrive at the next quantum dot at the same state that it was transported in. The molecular beam epitaxy at the chair of Applied Solid State Physics of the Ruhr Universitat Bochum prepared the samples and Grenoble and Tokyo structured and measured them.