Researchers from JILA, a joint institute of the University of Colorado Boulder and NIST, have developed a device that uses a small plate to absorb microwave energy and bounce it into laser light, calling this microscopic trampoline a crucial step for sending quantum signals over long distances.

“We’re anticipating a growth in quantum computing and are trying to create a link that will be usable for these networks,” says graduate student Peter Burns and one of two lead authors of the team’s study published in Nature Physics. The team’s research could one day help engineers link together huge networks of quantum computers, according to Burns.

Over the last decade, several tech firms have made inroads into designing prototype quantum chips that have the potential to be much more powerful than traditional computers. But getting the information out of such chips is a difficult feat, according to Burns.

One big challenge, he says, lies in translation. Top-of-the-line quantum chips like Google’s Bristlecone or Intel’s Tangle Lake send out data in the form of photons, or tiny packets of light, that wobble at microwave frequencies. Much of modern communications, however, relies on fiberoptic cables that can only send visible light.

The JILA team reports that zapping a small plate made of silicon-nitride with a beam of microwave photons causes it to vibrate and eject photons from its other end. But those photons now quiver at optical frequencies.

The researchers were able to achieve that hop, skip and jump at an efficiency of 47 percent, meaning that for every two microwave photons that hit the plate, close to one optical photon came out. That’s a much better performance than other methods for converting microwaves into light, such as by using crystals or magnets, Burns says.

He added that what’s really impressive about the device is its quietness. Even in the ultra-cold lab facilities where quantum chips are stored, trace amounts of heat can cause the team’s trampoline to shake. That, in turn, sends out excess photons that contaminate the signal. To get rid of the clutter, the researchers invented a new way to measure that noise and subtract it from their light beams. The work was done with a dilution refrigerator that cooled the trampoline to mK temperatures.

“What we do is measure that noise on the microwave side of the device, and that allows us to distinguish on the optical side between the signal and the noise,” Burns says.

The team will need to bring down the noise even more for the trampoline to become a practical tool. But the potential benefits are huge, says JILA’s Konrad Lehnert, a co-author of the new research. “It’s clear that we are moving toward a future where we will have little prototype quantum computers. It will be a huge benefit if we can network them together.”