Another step toward quantum computers: Using photons for memory

Scientists at Yale University have found a new way to manipulate microwave signals that could aid the long-term effort to develop a quantum computer, a powerful tool that would revolutionize information processing through unprecedented speed and power.

Like regular (classical) computers, quantum computers must be able to receive, store, and manipulate information in order to perform calculations. But the fragile nature of quantum information—which exists as a "0" or "1" or both simultaneously—poses challenges. In research published March 14 in the journal Nature, Yale physicists report an advance in developing memory mechanisms.

The advance involves photons, the smallest units of microwave signals, which can serve as a quantum computer's memory, like the RAM of a regular computer. Photons can carry and hold quantum information for a long time, because they interact weakly with the media they typically travel through—coaxial cables, wires, or air, for example. The weakness of these interactions prevents the photons from being absorbed by the medium and preserves the quantum information, once it's been encoded.

In the Nature paper, the researchers report creating an artificial medium in which photons repel photons, allowing for efficient, non-destructive encoding and manipulation of quantum information.