Wednesday 23 March 2011

A New Era in Super-Computing?

If you're looking for areas in which maths can be applied to the real world, look no further than computing and in particular the latest exciting advances coming from universities in the US.

At a meeting of the American Physical Society in Dallas, scientists from University of California, Santa Barbara have been demonstrating the latest steps on the road to a quantum computer.

A quantum computer, something that, as far as we know, has yet to be built, would be able to perform calculations on a scale that would vastly out-perform today's super-computers.

The UCSB device is one step along the road towards such a computer. It houses a chip containing 9 quantum devices, four of which are "quantum bits" or Qubits, which do the calculations. Later this year, the team hopes to increase the number of Qubits to 10. When scientists are able to increase the number of Qubits to about 100, they think the chip will be the basis of a viable, usable computer.

All of this opens the possibility that in the near future we'll have the power of today's super-computers on our desks, on our laps, even in our mobile phones.

For these developments, we owe a lot to Erwin Schroedinger, whose work on quantum physics and wave equation paved the way for the weird world of quantum mechanics.

At its heart, quantum computing depends on "super-position", which is the seemingly unnatural ability for a particle to be in two states at the same time. A particle spinning in one direction could be given a weak pulse of energy, which might be enough to set it spinning in the opposite direction, but maybe not. As long as the particle is not being observed or interacted with in any way, quantum physics says that the particle is in both states at the same time.

Now, we could use a whole line of these particles to represent the binary digits of a number. If a calculation is performed using a traditional computer, we would need to feed each number into the computer separately. But because a quantum computer can operate on particles in super-position, it can perform the calculation on all the possible combinations simultaneously. A number whose binary representation is 7 digits long is between 0 and 127. A traditional computer would need to do a calculation on each of these 127 numbers. A quantum computer could do them all at once.

But the power of quantum computing brings huge challenges for society. In fact, as things stand, a fully functioning quantum computer would jeopardise the stability of the world. This is because world commerce depends on the use of secure ciphers to protect and verify financial transactions. Additionally, many secure conversations between governments and government institutions are carried out using the same sets of ciphers. With the unimaginable computing power that quantum computing would bring, these ciphers, which we have previously considered unbreakable, would be rendered useless.

So the race is on: will the quantum computer arrive first, posing threats to international security and commerce? Or will a new quantum cryptography be developed first, securing transactions in a new unbreakable way? (It's another story, but such a form of encryption has already been shown possible over short communication distances. And it is absolutely unbreakable.)

Yesterday's science fiction really is tomorrow's reality.

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