Towards a quantum computer

IN A computer, with three bits, there are eight possible combinations of 1 or 0. But three bits in a digital computer can store only one of those eight combinations at a time.

Quantum computers, would be based on the strange principles of quantum mechanics, in which the smallest particles of light and matter can be in different places at the same time.

In a quantum computer, one `qubit' - quantum bit - could be both 0 and 1 at the same time. So with three qubits of data, a quantum computer could store all eight combinations of 0 and 1 simultaneously.

That means a three-qubit quantum computer could calculate eight times faster than a three-bit digital computer.

A University of Utah physicist Christoph Boehme and colleagues took a step toward developing a superfast computer based on the weird reality of quantum physics by showing it is feasible to read data stored in the form of the magnetic `spins' of phosphorus atoms.

`Spin' simplified

A simplified way to describe spin is to imagine that each particle contains a tiny bar magnet, like a compass needle, that points either up or down to represent the particle's spin.

Down and up can represent 0 and 1 in a spin-based quantum computer, in which one qubit could have a value of 0 and 1 simultaneously. In the new study, Boehme and colleagues used silicon doped with phosphorus atoms.

By applying an external electrical current, they were able to "read" the net spin of 10,000 of the electrons and nuclei of phosphorus atoms near the silicon surface.

A real quantum computer would need to read the spins of single particles But previous efforts, which used a technique called magnetic resonance, were able to read only the net spins of the electrons of 10 billion phosphorus atoms combined.

Personal computers today calculate 64 bits of data at a time. A quantum computer with 64 qubits would be 2 to the 64th power faster, or about 18 billion billion times faster.

Souce: The Hindu

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