The University of California-Santa Barbara researchers -- physicists Max Hofheinz, John Martinis and Andrew Cleland -- call their achievement a milestone in experimental quantum mechanics.

The scientists said they used a superconducting electronic circuit known as a Josephson phase qubit, developed in Martinis' lab, to controllably pump six microwave photons, one at a time, into the resonator. The photon number states, known as Fock states, had never before been controllably created, said Cleland.

"These states are ones you learn about in introductory quantum mechanics classes but no one has been able to controllably create them before," Cleland said.

The three scientists said their findings could help in the quest to build a quantum computer, which both government and industry have been seeking for a long time. A quantum computer could be used, among other things, to break encryption codes employed in secure communication.

"I think if they really build one of these quantum computers, there will definitely be resonators in them," Hofheinz said.

The research was reported in the July 17 issue of the journal Nature.