Because transistors will inevitably stop to shrink in size in the future, European researchers are studying atomic-scale computing. According to ICT Results, this would allow computer processes to be carried out in a single molecule. 'In theory, atomic-scale computing could put computers more powerful than today's supercomputers in everyone's pocket.' So far, the EU-funded team has already designed a simple logic gate with 30 atoms that perform the same task as 14 transistors. The project coordinator said: 'Atomic-scale computing researchers today are in much the same position as transistor inventors were before 1947. No one knows where this will lead.' So don't expect to use a computer based on molecular components anytime soon. ...
You can see above a diagram showing the various interconnections studied within by Pico-Inside project going from atomic level to millimeter scale: "1) molecule to atomic wire (atomic level) 2) atomic wire to a metallic island of a few monolayers high which links the atomic level and the nano level 3) metallic island to a thin metallic ribbon which links the nano level and the meso level 4) thin metallic ribbon to micro-electrode which links the meso level and the micro level 5) microelectrode to macroscopic wiring which links the micro level and the macro level." (Credit: C. Joachim, CEMES-CNRS) Here is a link to a larger version of this picture and another one to an image gallery related to the project.
The Pico-Inside project started in September 2005 with a budget of €5 million. Christian Joachim of the French National Scientific Research Center (CNRS)'s Center for Material Elaboration & Structural Studies (CEMES) in Toulouse, France, was the coordinator of the project. Joachim, who is the head of the CEMES Nanoscience and Picotechnology Group (GNS), is currently coordinating a team of researchers from 15 academic and industrial research institutes in Europe.
Now, why these researchers are trying to compute with molecules? Here is why. "Transistors have continued to shrink in size since Intel co-founder Gordon E. Moore famously predicted in 1965 that the number that can be placed on a processor would double roughly every two years. But there will inevitably come a time when the laws of quantum physics prevent any further shrinkage using conventional methods. That is where atomic-scale computing comes into play with a fundamentally different approach to the problem."
As I said above, the team designed a logic gate with 30 atoms. This is interesting, but what's next? [The researchers] "are focusing on two architectures: one that mimics the classical design of a logic gate but in atomic form, including nodes, loops, meshes etc., and another, more complex, process that relies on changes to the molecule's conformation to carry out the logic gate inputs and quantum mechanics to perform the computation. The logic gates are interconnected using scanning-tunnelling microscopes and atomic-force microscopes -- devices that can measure and move individual atoms with resolutions down to 1/100 of a nanometre (that is one hundred millionth of a millimetre!). As a side project, partly for fun but partly to stimulate new lines of research, Joachim and his team have used the technique to build tiny nano-machines, such as wheels, gears, motors and nano-vehicles each consisting of a single molecule."
As you can deduct from the short excerpts above, commercial applications will not emerge before a long time.
Sources: ICT Results, December 19, 2008; and various websites
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