What's in the photo?
The cavity mirrors are above and below, while the overlaid white cones indicate the optical access available for looking into the cavity. And the two things sticking in are antennas we use to characterize in the cavity.
A Room with a View — for light
Imagine a hall of mirrors where light bounces millions of times without fading. Physicists at Stanford University have built such a device, known as a cavity, that stores light for nearly 20 million round trips between two highly reflective mirrors. While such cavities aren’t new, this one also provides optical access — the ability to shine lasers in from many angles.
Why is this useful? One promising path toward larger quantum computers relies on trapping arrays of individual atoms. As these arrays grow, the challenge is to make distant atoms “talk”. Inside a cavity, light can be the messenger: information from one atom can be converted to light, which lingers long enough for another atom to pick up.
But trapping atoms requires optical access, which usually allows stored light to leak faster. To avoid this leakage, the researchers carefully positioned two superconducting mirrors which, when cooled to mere degrees above absolute zero, become extremely good reflectors for millimeter-waves — an invisible “color” of light used in 5G communication and airport security scanners.
By combining exceptional light storage with optical access, the new cavity overcomes a long-standing tradeoff and paves the way toward larger quantum computers and new explorations of exotic quantum systems.
