Quantum computing edges nearer

Researchers from the department of electrical engineering at the University of Nebraska-Lincoln have patented a technique that produces quantum dots. The tiny structures that 10,000 times smaller than the thickness of a human hair but are said to offer staggering potential.

‘As an example of what quantum computers can do, let’s say that you wanted to build a computer that has two to the 1,000th power (21,000) bits of data. You could never build a classical computer to do that because the number two to the 1,000th power is larger than the number of atoms in the known universe,’ said Supriyo Bandyopadhyay’, head of the Nebraska group. ‘With a quantum computer, all you would need is just 1,000 atoms to build a computer that powerful,’

In contrast, conventional computers produce large amounts of heat and have to refresh their data several times a second to avoid losing it.

A quantum computer would be able to do all that because of how the laws of physics change at the atomic level.

‘There are some fundamental properties of any quantum mechanical system, namely the ability of the quantum system to exist simultaneously in different states — the power to be in two different places at the same time, a phenomenon called ‘quantum parallelism,” Bandyopadhyay explained. ‘You have to be able encode bits of information in the various states of the atoms in an appropriate way so that you can do quantum mechanical manipulations with them.’

Bandyopadhyay and five fellow UNL electrical engineers have been working on quantum computer research for about three years and have succeeded in demonstrating new types of computer memory.

But Bandyopadhyay said his team is probably five years away from being able to demonstrate a small-scale quantum computer in the lab, while commercial versions probably won’t be available for 20 to 25 years.

Another breakthrough that Bandyopadhyay and colleagues are working on will probably be implemented much sooner.

Quantum dots can also be used to create high-speed, non-linear optical devices that would shield satellites from laser attack and improve the military’s abilities in electronic warfare, infrared imaging, night vision and surveillance.

‘If you shine a light on an object, some of the light is reflected. Non-linear optics means that the fraction of the reflected light depends on the intensity of the incident light,’ saidBandyopadhyay. ‘By changing the intensity of the incident light, you can change the fraction of the incident light that is reflected.

Bandyopadhyay and his colleagues take a piece of aluminium, subject it to electro-chemical processes and the quantum dots spontaneously appear on the surface of the aluminium.

The chemical solution has to be just the right mixture, and the electrical current has to be at just the right power level and used for exactly the right length of time. Otherwise, the dots won’t arrange themselves in the perfectly ordered rows that Bandyopadhyay and his team need.

‘There has been a whole lot of experimentation and it’s still going on,’ Bandyopadhyay said. ‘We’ve been working on this for five or six years now and it’s far from perfect. Maybe in another five or six years we can perfect it.’