Quantum devices

Silicon chips that exploit the unique properties of quantum physics could be common components in laptops and smart phones within a few years, say scientists. British-led technology is set to revolutionise computing using circuits that operate with light instead of electricity, it is claimed.

For the first time, they will offer a practical way of harnessing subatomic interactions so strange they spooked Albert Einstein.The result could be blindingly fast search engines, encryption systems that cannot be cracked, and computers vastly more powerful than anything in use today.

Super-secure communication devices expected to appear in the next three years could effectively end hacking and identity theft.

In another decade, quantum computers could be outperforming their conventional counterparts.
And by 2025 quantum circuits might be everywhere - sitting inside laptops and phones, helping to design new drugs and smart materials, predicting the weather with unprecedented accuracy, and keeping bank accounts and sensitive information safe.

'It had previously been thought that a large-scale quantum computer will not become a reality for at least another 25 years,' said Professor Jeremy O'Brien, director of the Centre for Quantum Photonics at the University of Bristol.

'However, we believe that, using our new technology, such a device, in less than 10 years, will be performing important calculations that are outside the capabilities of conventional computers.' An ordinary computer relies on logic gates - essentially switches - that are either on or off and which encode data into 'bits' represented by ones and zeros.

But a quantum computer's switches can be on, or off, or simultaneously on AND off.A 'qubit' can exist as a zero, a one, or a 'superposition' of both these states at the same time. Multiple qubits can be in numerous inbetween states.

This is possible because of quantum effects only seen at the subatomic level that appear to defy common sense.Particles such as photons, packages of light, can be in two places at once or 'entangled' so they influence each other instantaneously, no matter how far apart they are.

Einstein found entanglement so hard to swallow he dismissed it as 'spooky action at a distance'.Prof O'Brien's team has found a way to build photon-channelling quantum circuits out of silicon, the cheap material used in computer chips all over the world.

This opens up the possibility of mass-producing quantum chips that can be used alongside ordinary microelectronic components.The extra cost of producing a mobile phone containing one or two quantum circuits would be minimal, according to the scientists.

They have already established promising partnerships with leading electronics companies Nokia and Toshiba.'Using silicon to manipulate light, we have made circuits over 1,000 times more complex than current glass-based technologies,' said Dr Mark Thompson, deputy director of the Centre for Quantum Photonics.

'This is very much the start of a new field of quantum-engineering, where state-of-the-art microchip manufacturing techniques are used to develop new quantum technologies and will eventually realise quantum computers that will help us understand the most complex scientific problems.'

The team will be showing off their quantum circuits at the British Science Festival, which opens at the University of Aberdeen tomorrow.One key advantage of quantum computing is that it allows for encryption systems that are inherently impossible to break.

Any disturbance of such a system would immediately become obvious because of the way quantum effects 'collapse' when observed. In a similar way, a tossed coin is immediately revealed as 'heads' or 'tails' when its spinning state is disturbed.
But the 'killer app' for quantum computers was simulating the properties of molecules, said Dr Thompson.

Such problems grow more difficult to solve at an exponential rate, so they quickly become out of reach for conventional computers.Quantum computers can handle much greater levels of complexity, enabling scientists to model molecules for medicines or smart materials without having to go through laborious and costly trial and error screening.