A DISCOVERY made by scientists at the University of Manchester, England, in collaboration with international colleagues marks a major breakthrough that could pave the way for a new type of high-speed computer.
Professor Richard Winpenny at Manchester's School of Chemistry and the team of researchers at other European centres have discovered a phenomenon that could hold the key to creating the first practical quantum computers.
Today's computers work by manipulating bits that exist in one of two states: a 0 or a 1 (similar to an electrical switch that is either on or off). Quantum computers are not limited to two states; they encode information as quantum bits, or qubits. A qubit can be a 1 or a 0, or it can exist in a type of state that is simultaneously both 1 and 0 or somewhere in between.
Qubits represent atoms that are working together to act as computer memory and a processor. Because a quantum computer contains such elements that can be in multiple states simultaneously, it has the potential to be millions of times more powerful than today's most powerful supercomputers.
The inherent “parallelism” existing in a quantum computer would allow it to work on a million computations at once, although the modern desktop PC can only work on one at a time.
Quantum computers also exploit an aspect of quantum mechanics known as entanglement.
One problem with the idea of quantum computers is that trying to detect the state of the subatomic particles could inadvertently change their value. But in quantum physics, if an outside force is applied to two atoms, it can cause them to become entangled. If left alone, an atom will spin in all directions; but the instant it is disturbed it chooses one spin, or one value.
At the same time, the second entangled atom will choose an opposite spin, or value. This phenomenon allows scientists to detect the value of the qubits indirectly.
The processing speed of the quantum computer would be especially valuable in factoring large numbers, and therefore extremely useful for encoding and decoding information and for searching very large databases in a fraction of the time that it would take a conventional computer.
It should be pointed out that quantum computing is still in its early stages of development; the technology needed to create a practical quantum computer is years away.
Significantly, Professor Winpenny and the research team have for the first time demonstrated how metal-containing rings that show properties necessary to act as qubits can be linked together using both organic and metal-organic fragments.
Their breakthrough, which results from three years' research, could help speed the development of practical quantum computers that will require magnetic “quantum gates” - a more advanced version of the logic systems found in conventional modern computers - to function efficiently.
Linked cage complexes such as the qubit rings could potentially be used as such gates allowing practical quantum information processing, explained Winpenny.
“Linking these molecules not only gives us a much better understanding of how these molecules interact but it also gives us more control over how they interact - which is essential if we are to ever successfully implement quantum gates,” Professor Winpenny said.
“This is the start rather than the finish in terms of the development of a quantum computer, but now that we have shown we can do this, it gives us clear targets. The immediate targets are the incorporation of a 'switch' between the qubits that would allow simple operations to be performed, and the improvement of the qubits themselves.”
The researchers found that the qubit rings, when attached using a hydrogen bond, remain stable in a rested state. They also found that the rings could be brought into close proximity without changing their magnetic behaviour due to through-space exchange.
This leads to the possibility of a switch being incorporated that uses exchange through electrons within the bonds of molecules.