Monday, 13 February 2012

Electron freedom could spark new computing

A new kind of quantum computing could now be possible given the latest discovery about the way electrons interact.

Physicist Dr Giuseppe Tettamanzi, from the University of New South Wales, and colleagues, report their findings this week in the journal Physical Review Letters.

"Our work hints that the orbital degree of freedom can be used for quantum logic, as in quantum computation, and there may be other applications," says Tettamanzi, whose paper is available on the pre-press website

Classical computers use millions of transistors on silicon chips that flip on and off, creating a series of 1's and 0's, according to whether current flows through them or not.

The aim of quantum computing is to use the individual properties of electrons to increase the power of data processing.

To date, quantum computing has sought to exploit the charge of electrons, or their spin (which can be either up or down), to create 1's and 0's.

But Tettamanzi and team have now shown that another property of electrons could instead be used to create 1's and 0's.

This property is the electron's so-called 'orbital degree of freedom', which describes its location around the nucleus.

The researchers have demonstrated that interaction between electrons with different orbital degrees of freedom can open a new transport channel in a silicon-based transistor.

While this so-called "Kondo effect" in itself is not obviously useful, the fact that it can be caused by orbital degree of freedom is exciting.

Previously the effect was only known to be caused by electron spin, which suggests orbital degree of freedom could be used, like spin, to develop quantum computers.

Tettamanzi and colleagues also applied a powerful magnetic field (10,000 times higher than Earth's magnetic field) and observed a mathematical symmetry in the system, which is something normally only seen in very expensive experiments, such as those carried out at CERN.

Most importantly, the researchers used a commonly-available silicon-based transistor, which suggests any quantum based computer using orbital degrees of freedom will be commercially viable.

"It's an everyday system, not a very complex system, something that we get from a factory that's made silicon devices for industrial uses," says Tettamanzi.

"There are already billions of dollars of investment in silicon facilities, so if you do something with silicon it will be much easier for it to become an everyday device, because there is already all the infrastructure available."

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