What’s the Holdup: In the late 1980’s and early 1990’s quantum computing fell into a “so what?” category. There was no progress because no one could think of any uses for it. Then, in 1994, Peter Shore at AT&T; came up with the killer app for quantum computers. He proved that quantum computers would be very good at factoring numbers down to their prime number constituents. And since factoring prime numbers is the basis of most modern computer security, a quantum computer could be the ultimate code breaker. Needless to say, people got interested.
Since then, the focus has been overcoming engineering challenges like keeping the quantum particles isolated enough from the outside world to hold multiple quantum states.
“It's not like going from a Pentium II to a Pentium III,” said Raymond Laflamme, director of the Institute for Quantum Computing, “it's a very different way of looking at how information is handled.”
When Can I Get One: Said Laflamme, “When people do predictions on the scale of 20 or 30 years, 20 or 30 years later others always look back and laugh at them. I think it will take 20 years to really understand the system. But you had asked me 10 years ago, I would have said 50 or 100 years.” So I guess we’re at least moving in the right direction.
[At left: The first transistor computer. This prototype was operational in 1953.]
University of ManchesterThe arrival of superfast quantum computing is closer following recent breakthroughs by an international team led by researchers from the University of New South Wales. Quantum computing relies on being able to control and observe the behaviour of quantum particles – for instance individual electrons - to deliver enormous processing power. In the two new breakthroughs, researchers have for the first time demonstrated two ways to deliberately place an electron in a nano-sized device on a silicon chip.
The achievements set the stage for the next crucial steps of being able to observe and then control the electron’s quantum state or “spin”, to create a quantum bit. Multiple quantum bits are coupled to make up the processor of a quantum computer.
Professor Andrew Dzurak, the NSW Node Director of the Australian National Fabrication Facility at UNSW, and Dr Andrea Morello, Manager of the Quantum Measurement and Control Chip Program at the ARC Centre of Excellence for Quantum Computer Technology, were able to accurately localise a single electron in silicon without it being attached to an atom. This “artificial atom” is known as a “quantum dot”
Dr Morello says the quantum dot was similar in principle to using a natural atom.“However this method avoids the difficulty of having to introduce single atoms in precise positions in the silicon chip,” he said.
In a separate project, the researchers, used “nature’s own way” to localise electrons, by binding them to single atoms. “Individual phosphorus atoms have been deliberately introduced in a nanometre-size silicon transistor. This special ‘single-atom transistor’ works by letting single electrons hop on and off the phosphorus atom, one after the other in a controllable way. A quantum bit can be formed by choosing to leave the electron on the atom, and using its spin as carrier of quantum information,” Dr Morello said.
Quantum computing’s power comes from the fact that electrons can have a spin pointing in two opposite directions, in the same way that zeroes and ones represent data in today’s computers. However electrons can also hold intermediate quantum states, or “spin” positions and, when coupled together, can deliver an exponential increase in their ability to represent data.
Dr Morello said the two breakthroughs were “very important results” and, while it was still hard to say when a quantum computer would become reality, recent progress was very encouraging. “The stream of successful experiments that we are achieving is giving us a lot of comfort that we are going in the right direction,” he said.
“While the development of a quantum computer is like making a very long journey, we feel now like we are not just walking but running.”
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