BBC

Ottawa -Scientists say they have obtained the best evidence yet for an important quantum physics phenomenon inside a $15m computer built by a Canadian firm.

D-Wave claims it has built the first practical quantum computer, a type of machine that could solve complex problems faster than is possible today. Scientists say they have shown that an effect called ‘entanglement’ is present in eight units of quantum information. Entanglement is a key step towards building a practical platform.

The results have just been published in the peer-reviewed journal Physical Review X. D-Wave, based in Burnaby, outside Vancouver, has courted controversy with its claim to have built a practical quantum computer, a feat that was thought to be decades away. Quantum computing exploits the strange physics of quantum mechanics, which takes hold at tiny (atomic or sub-atomic) scales.

The basic units of information in classical computers are called ‘bits’ and are stored as a string of 1s and 0s, but their equivalents in a quantum system - qubits - can be both 1s and 0s at the same time. But the qubits need to be synchronised using a quantum effect known as entanglement, which Albert Einstein dubbed ‘spooky action at a distance’. ‘This is the first peer-reviewed scientific paper that proves entanglement in D-Wave processors,’ Dr Colin Williams, director of business development at D-Wave, told BBC News.

‘What's even more remarkable is that this is the largest demonstration of entanglement in any quantum, superconducting computing scheme so far,’ he said. ‘It's a big achievement for the field.’ They also showed that the entanglement was stable, persisting throughout a critical operation of the processor. The vast majority of academic research into this area of computing is based around the model of ‘quantum gates’. These are the quantum equivalents of the logic gates that form the building blocks of circuits in classical computing.

But D-Wave has taken a different approach known as quantum annealing. On a particular type of mathematical challenge known as an optimisation problem, annealing can, in theory, short-cut classical computers to the best answer.