Scientists closer to creating quantum computers

LONDON, 19 January 2011, (Reuters) - Scientists have moved a step closer to creating ultra-fast quantum computers by generating 10 billion bits of quantum entanglement in silicon for the first time.

The achievement in silicon, the basis of the computer chip, has important implications for integration with existing technology, according to a team from Britain, Japan, Canada and Germany whose study was published in the journal Nature on Wednesday.

"Creating 10 billion entangled pairs in silicon with high fidelity is an important step forward for us," said John Morton of Britain's Oxford University, who led the team.

"We now need to deal with the challenge of coupling these pairs together to build a scalable quantum computer in silicon."

Scientists believe that super-fast quantum computers, based on quantum bits, or qubits, will be able to test many possible solutions to a problem at once.

Conventional computers based on binary "switches", or bits, can only do one thing at a time.

Quantum entanglement involves the notion that particles can be connected in such a way that changing the state of one instantly affects the other, even when they are miles apart.

Albert Einstein once famously described it as "spooky action at a distance".

Other areas of quantum-related research include ultra-precise measurement and improved imaging.

The researchers used high magnetic fields and low temperatures to produce entanglement between the electron and the nucleus of an atom of phosphorous embedded in a silicon crystal.

The procedure was applied in parallel to a vast number of phosphorous atoms, they said.

The electron and the nucleus behave as a tiny magnet, or so-called "spin", each of which can represent a bit of quantum information. When controlled in the right way, these spins can interact with each other.

"The key to generating entanglement was to first align all the spins by using high magnetic fields and low temperatures," said Oxford's Stephanie Simmons, who also worked on the team.

"Once this has been achieved, the spins can be made to interact with each other using carefully timed microwave and radiofrequency pulses in order to create the entanglement, and then prove that it has been made."