Tiny quantum storage device fits on a chip

A newfangled data storage device, which takes up less than a millionth the amount of space of its predecessors, could be a key component of futuristic communication systems.

Scientists fashioned a tiny crystal that stores snippets of quantum information — which unlike computer data “bits” that come only in 0s and 1s, can also exist as both 0 and 1 simultaneously. This crystal is the first quantum memory device of its kind that could fit on a chip alongside nano-sized instruments for detecting and sending signals written in quantum bits. This work, reported online August 31 in Science, improves prospects for establishing a widespread, ultrasecure network of quantum communications.

Crystal quantum memory devices hoard data by absorbing photons, each of which carry one quantum bit, or qubit, of data. Generally, the bigger the chunk of crystal, the greater the chance that one of its atoms will absorb a photon streaking through the material. For a typical, cube-shaped crystal to snare photons as well as the new storage device, it would have to be about a millimeter across, says study coauthor Tian Zhong, a molecular engineer at the University of Chicago. But the crystal that Zhong and colleagues built is only about 10 micrometers long and 0.7 micrometers wide — about as wide as a bacterial cell.

The secret to this storage device’s tiny size is its shape, which resembles a Toblerone chocolate bar: a triangular prism with notches etched along the top. “The grooves towards the ends of the [crystal] collectively behave as two mirrors, one on each side,” Zhong says.