Another Milestone for Quantum Computing

Quantum computing could offer computing performance orders of magnitude more powerful than our current methods, the instant transmission of messages at great distances, and a perfectly secure means for transferring data between computing nodes.

The sticking point—it's exceedingly difficult to accomplish and so far, successful experiments in quantum computing, which seeks to leverage the "spooky action" of entangled sub-atomic particles, have been the stuff of laboratories, not real-world environments.

But this week, scientists in Australia announced that they have "developed the first silicon quantum technology capable of holding data with over 99 per cent accuracy," according to Discovery News.

This is important, the researchers wrote in a pair of papers appearing in the current issue of Nature Nanotechnology, because it potentially paves the way for creating reliable building blocks for transistor-based quantum computers, using the material most commonly used today to build conventional computers.

The scientists actually developed two separate methods for fashioning a quantum bit, or qubit, which is the name for the element providing information storage in a quantum computer.

In the first method, the Australian team refined a technique used to turn phosphorous atoms into qubits, Discovery News noted, improving the reliability of data retention from just 50 percent to 99.99 percent. The second method involves "turning a silicon transistor into an 'artificial atom' qubit giving an accuracy of 99.6 per cent," the science site reported.

"We have demonstrated that with silicon qubit we can have the accuracy needed to build a real quantum computer. That's the first time this has been done in silicon," Discovery News quoted one of the authors, Prof. Andrew Dzurak of the University of New South Wales, as saying.

The scientists said they were also able to increase the length of time with which information was retained in their silicon qubits, a function known as "coherence time," the site said.

Dzurak explained to Discovery News how he and his colleagues were able to improve the reliability of their silicon qubits using a phosphorous atom.

"In natural silicon each atom also has its own spin which affects the phosphorous atom, which is why the accuracy was only 50 per cent," he told the site. "We solved the problem by removing all the silicon 29 isotopes that have magnetic spin leaving only silicon 28, which has no magnetic spin to influence the phosphorous, giving us an accuracy of 99.99 per cent."

With their other method, the team trapped an electron in a silicon transistor of the type used in computer chips today, Dzurak said.

"This lets us use exactly the same sort of transistor that we use in computer chips and operate it as a qubit, opening the potential to mass-produce this technology using the same sort of equipment used for chip manufacturing," he said.

Quantum entanglement allows for entangled particles like qubits to immediately share information even if separated by great distances in a seeming loophole in the universe's speed limit, the speed of light. Entanglement was famously described by Albert Einstein as "spooky action at a distance," and Prof. Ronald Hanson, head of a Dutch research team experimenting with quantum computers, called it "arguably the strangest and most intriguing consequence of the laws of quantum mechanics."

The efforts of the Australian team build upon a rash of breakthroughs in quantum computing achieved by researchers in recent years.

Earlier this year, Hanson's team achieved what they said was true quantum teleportation, transmitting information contained in one qubit to another entangled qubit about 10 feet away "without the information having travelled through the intervening space," the researchers said.

That achievement came after similar quantum teleportation experiments involving electrical currents and photons bore fruit a year earlier for Swiss and Japanese scientists.