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NEC researchers in Japan, working with the RIKEN Institute of Physical and Chemical Research, have announced just such a breakthrough. They claim to have successfully experimented with conditional logic gate operations involving two coupled quantum bits, or qubits (which use a quantum superposition of both the '0' and '1' states).

NEC has a track record in this field - back in 1999 it successfully controlled the quantum state of one qubit. It claims this was the first demonstration of a one-qubit rotation gate in solid-state devices. And back in February of this year, NEC/RIKEN demonstrated the first quantum entanglement in a 2-qubit solid-state device.

The

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researchers are now proposing to implement a superconductors-based quantum gate known as the controlled-NOT (C-NOT), which complements the second bit of a pair if the first bit is 1 and leaves the bit unchanged otherwise.

NEC states that it has been theoretically proven that only two kinds of gate operations are needed for quantum computation. It says that these are the one-qubit rotation gate, controlling the state of one qubit, and the C-Not gate, which is a conditional gate for two qubits.

Heading the latest research was Jaw-Shen Tsai of the NEC Fundamental Research Laboratory and the RIKEN Institute, with the work taking place at the Institute's Macroscopic Quantum Coherence Laboratory

Version 1.0 of Quantum Logic Gates will be appearing in desktop PCs next year. Only joking, quantum computing remains a distant prospect, but NEC hails this as a world's first and a 'major step' towards the realisation of practical techniques.

Details of the research will be published in the British science journal Nature.

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