Boffins play ping-pong with single electron Researchers at Cambridge University have managed to bat an electron back and forth along a wire in a high-tech game of ping-pong that could help out with quantum computing. The findings, published in Nature, showed the boffins were able to exercise a high level of control over the path of an electron in an electronic circuit …
I could have sworn that one of the things we learned in physics was that electric current barely "flows" per se, that the individual electrons in a wire move ponderously slowly. Or should that be filed in the same round filing cabinet as nonsense about plugholes and coriolis effects?
You're right that the speed that electrons move at in a normal wire is pretty slow - for a DC current they move at what's called the drift velocity, which for most metals is something like a few mm per hour if I remember correctly. Here the electrons are moving at about the speed of sound (2.7 km/s in gallium arsenide, give or take)
The thing is, these single-electron devices operate in a totally different regime to normal electrical devices. The idea is to use the quantum properties of a few electrons (probably their spin, though that's not looked at in this experiment) to form the building blocks of a quantum computer. And the sort of technique demonstrated here could be useful in moving those building blocks around - think, for example, of transferring info between a CPU and RAM in a normal computer.
It's not the burst of sound itself which carries the electron: these devices work because gallium arsenide is piezoelectric (ie if you deform it slightly, it produces an electric field). The deformation of the crystal due to the sound wave thus leads to a travelling electrical wave which travels along at approximately the speed of sound, and that's what moves the electron backwards and forwards.
It would seem to me that this would be an absolutely great path redirection method.
Hit the electron on one end of the table, bounce it off the side correctly, and it lands at the end of the path it should continue on. Next stop, turn the rectangle into a tube, after that an electron light emitting surface on the end of a fiber interface.
Besides, conceptually, I've never met anyone who likes Billiards that didn't mind losing 90% of the time and kept trying.
Bound to keep a scientist in bucks for a lifetime.
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