Quantum code breaking

A crucial step in a procedure that could enable future quantum computers to break today's most commonly used encryption codes has been demonstrated by physicists at the US Commerce Department's National Institute of Standards and Technology (NIST).

As reported in the May 13 issue of the journal Science, the NIST team showed that it is possible to identify repeating patterns in quantum information stored in ions (charged atoms). The NIST work used three ions as quantum bits (qubits) to represent 1s or 0s--or, under the unusual rules of quantum physics, both 1 and 0 at the same time.

Scientists believe that much larger arrays of such ions could process data in a powerful quantum computer. Previous demonstrations of similar processes were performed with qubits made of molecules in a liquid, a system that cannot be expanded to large numbers of qubits.

"Our demonstration is important, because it helps pave the way toward building a large-scale quantum computer," says John Chiaverini, lead author of the paper. "Our approach also requires fewer steps and is more efficient than those demonstrated previously."