December 10, 2008 Physicists have taken a significant step toward creation of quantum networks by establishing a new record for the length of time that quantum information can be stored in and retrieved from an ensemble of very cold atoms. Though the information remains usable for just milliseconds, even that short lifetime should be enough to allow transmission of data from one quantum repeater to another on an optical network.

The new record — 7ms for rubidium atoms stored in a dipole optical trap — was reported December 7 in the online version of the journal Nature Physics by researchers at the Georgia Institute of Technology. The previous record for storage time was 32ms, a difference of more than two orders of magnitude.

“This is a really significant step for us, because conceptually it allows long memory times necessary for long-distance quantum networking,” said Alex Kuzmich, associate professor in the Georgia Tech School of Physics and a co-author of the paper. “For multiple architectures with many memory elements, several milliseconds would allow the movement of light across a thousand kilometers.”

Fluorescence of laser-cooled neutral rubidium 85 atoms collected by a backlit CCD array. These ultracold atoms are collectively used to store quantum information. (Source: Georgia Tech/Kuzmich Research Group)

The keys to extending the storage time included the use of a one-dimensional optical lattice to help confine the atoms and selection of an atomic phase that is insensitive to magnetic effects.

The research was sponsored by theNational Science Foundation, the A.P. Sloan Foundation and the US Office of Naval Research.

Ran Zhao and Yaroslav Dudin, graduate students in the Georgia Tech School of Physics, adjust optics in a system used to study quantum memory. (Georgia Tech Photo: Gary Meek)