Single atoms line up for quantum computer

26 August 2001

in 2001

Australian researchers have made a break through in developing a quantum computer – a computer so powerful that it calculates in seconds what it would take current supercomputers billions of years.

University of New South Wales PhD student, Jeremy O’Brien is part of a research team at the Centre for Quantum Computer Technology who have put a row of single phosphorus atoms onto a silicon surface.

Such arrangements of single phosphorus atoms are part of the essential technology, likely to form the ‘engine room’ of an incredibly powerful quantum computer.

Mr O’Brien said a quantum ‘bit’ or ‘qubit’ is the building block of a quantum computer. While a ‘bit’ in current computers can be 0 or 1, a qubit can be in a quantum mechanical ‘superposition’ of these two states – something like being in both states at once.

“When entangled, qubits behave in concert with each other and somehow become ‘wired’ together through their interactions,” he said. “While current computers process information in a series of steps, quantum computers process all possible inputs in a single step.”

Current research has demonstrated the principles of quantum computing on a few qubits but the challenge remains to scale the number of qubits up.

“This makes the phosphorus in silicon approach, with its ease of integration into existing technology, and promise of scalability, very attractive,” Mr O’Brien said. “The spin of the single phosphorus atom nuclei form the qubits embedded in high purity silicon crystal.”

Mr O’Brien has produced a precise array of single phosphorus atoms on a silicon surface with a spacing of the order of billionths of a metre.

He did this by covering a clean silicon surface with hydrogen atoms. He then used a scanning tunnelling microscope to remove single hydrogen atoms at precise locations on this surface. Exposure to phosphine gas results in the attachment of single phosphorus atoms at these locations. This represents a significant step towards realising the wonder of quantum computing.

Mr O’Brien announced the results of his research today (26 August) at the 10am ScienceNOW! media conference. He will present his research in more detail to the public on Sunday 26 August in the ScienceNOW! session commencing at 1.30am.

Jpeg images are available of microscope photos of phosphorus atoms on a silicon surface. A diagram simply explaining the concepts of quantum computing is also available.

Jeremy O’BrienĀ  is available for interview at today’s (26 August) 10am ScienceNOW! media conference held in the media room at ScienceNOW! at the Melbourne Exhibition Centre – follow the signs in the foyer.

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