Marrying matter and light

Despite centuries of scientific scrutiny, the ways in which light and matter affect each other remain only partly understood. To get a look at the most fundamental of light-matter interactions, physicists have been trapping one atom and one photon together between tiny mirrors (SN: 3/18/00, p. 191: Available to subscribers at Photon-in-a-box slings atom into orbit). In such experiments in quantum physics, the photon and atom repeatedly merge and disengage, forming a blended entity of matter and light.

Now a U.S.-based research team and a Netherlands-Japan team are turning to an alternative experimental approach based on so-called artificial atoms: micrometer-scale structures made of metals that conduct electricity with no resistance. In a pair of independent reports in the Sept. 9 Nature, the teams present evidence that a microwave photon can merge with one of these artificial atoms and form a hybrid of light and matter.

Normally, photons have little or nothing to do with one another, but in these entities the scientists expect to see exotic events, such as the merging of two photons to form a more-energetic photon.

Robert J. Schoelkopf of Yale University, a leader of the U.S.-based team, says he and his colleagues plan on extending the work into potentially practical arenas, among them quantum-information processing. For example, he notes, it might be possible to make microchips bearing multiple artificial atoms that together can perform calculations by influencing one another’s quantum states through a shared photon.

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