Overlooked element could be part of dream team for quantum computing

Aug 16, 2010
Overlooked element could be part of dream team for quantum computing
A bismuth atom in one slice of a silicon crystal. The large light green cloud shows the possible positions of the bound electron’s wave function, and the purple arrow is its spin. The bismuth nuclear spin (blue arrow) can tilt in ten different directions, shown in red and yellow. Artwork by Manuel Vögtli (LCN).

A team of scientists based at the London Centre for Nanotechnology and the National High Magnetic Field Lab (NHMFL) in Florida has discovered a new and more efficient way to encode quantum information within silicon.

Despite being compatible with the silicon chips all around us, the chemical element has been overlooked to date in favour of phosphorus atoms in the race to quantum technologies. This is because today’s microelectronics use phosphorous dissolved in silicon.

However, the researchers have now found that bismuth atoms outperform phosphorus atoms. Bismuth is the heaviest stable atom and has a correspondingly large nuclear ‘spin’. Its quantum spin is like a tiny compass needle that can exist in one of ten states corresponding to different tilts (see image below) instead of the two directions available to a phosphorus nucleus. This allows bismuth nuclei to store much more than phosphorous nuclei.

The research, which is described in the journal and in a forthcoming article in , reveals the potential of bismuth atoms for building a quantum computer.

The observations lead to the suggestion of a ‘dream team’ using both bismuth and phosphorus atoms in silicon. As they are different, they can be manipulated independently. Bismuth would store quantum information while phosphorus controls the information flow.

Lead author Dr Gavin Morley of the London Centre for Nanotechnology said: “The experimental hurdles we’ve overcome in our research include using bismuth in silicon for the preparation, control and storage of quantum information. In this case bigger is better because the larger nucleus of bismuth provides more room for storing quantum information.”

Co-author Marshall Stoneham said: “If a quantum computer could be built, it could solve some problems that have long been regarded as impossible. Having one type of atom for storing quantum information in , and another type for controlling it is like bringing a second person into a one-man conversation: much more interesting!”

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not rated yet Aug 16, 2010
not to mention 10^10 is a heck of a lot bigger than 3^10 -- if you are using ten atoms/qubits
3.8 / 5 (4) Aug 17, 2010
Don't you just LOVE that we have the ability to do science? And that there are gazillions of different ways to approach something?
Great discovery!
not rated yet Oct 13, 2010
talk of quantum computers over the years has gone from near science fiction to near reality. the continual discoveries in this field is just amazing.