- Powerful computers that run without electric
power could be possible in the future.
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- Research shows that computer circuits
can be built to work without electricity. A tiny initial charge is all
that is needed.
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- The new "logic gates" exploit
the charge of captured electrons to set off a domino-like cascade of change
in stored information.
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- They have been developed by scientists
at the University of Notre Dame in Indiana, USA.
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- Most experts believe that standard computer
processors can only be miniaturised so far, before classical physics fails
and strange quantum effects take over. This new technology could be a replacement
as it can in theory be shrunk to the molecular scale.
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- Dr Charles Smith, in the Physics Department
at the University of Cambridge, UK, told BBC News Online: "It is very
nice work to show that you can make a gate using single electrons which
move around. This has the advantages of switching very quickly and using
very low power."
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- Quantum dots
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- The key to the new technology is a cell
with four tiny dots of material which can capture electrons. They are arranged
as a square. When two electrons are put into the cell, they repel one another
and end up positioned across one diagonal or the other.
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- These two positions correspond to the
binary "0" and "1" used in computing. Today's computers
use on and off transistors for zeroes and ones.
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- By placing another quantum-dot cell next
to the first, the repulsive electrical charge of the electrons allows the
information to be passed on without needing an electrical current.
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- Possible in principle
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- Chains of the cells would be the "wires"
in the new computers and could be arranged to make logic gates. The researchers
at Notre Dame built a simple type of gate to show that the principle of
this kind of computing is sound. Their work is published in Science magazine.
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- However, Dr Smith comments: "Other
research shows you probably have to control the size of the quantum dot
which holds your electron to such tiny resolution that it may well turn
out to be rather impractical.
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- "But there is a chance that the
same architecture might work with something other than electrons, such
as tiny magnets."
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- In addition to these, another major obstacle
will need to be overcome. At the moment, the circuits only work at -272.9
degrees Centigrade, just above absolute zero.
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