Pie in the Sky

It’s pretty obvious, by now, that the quantum frontier is the next big thing.

We hear a lot nowadays about quantum computers and quantum cryptography. Quantum is truly the next era in science and technology, and now researchers from the National University of Singapore and the University of Strathclyde have successfully tested the technology for the next next big thing—a satellite-based global quantum network.

Here’s what’s going on: The idea is to use the quantum property of entanglement—what Einstein famously dismissed as “spooky action at a distance”—to encode information that is potentially unhackable and 100% secure. It will also be used to link up quantum computers into a worldwide super-internet, a global tissue of lightning-fast, non-binary computation that will make our current internet seem like the sluggish and confused mental fumblings of an inebriate.

There’s just one problem: such a network will probably need to be space-based. Which poses its own unique challenges.

The Quantum Future

The first step toward creating a global, satellite-mediated quantum network required actually constructing a satellite capable of performing the needed quantum experiments.

To this end, the researchers created SPEQS (Small Photon-Entangling Quantum System), an innovative technology pathfinder that splits photons produced by a BluRay and measures the properties of the entangled pair.

Since the whole experiment was designed to fit within a CubeSat nanosatellite—an inexpensive satellite platform weighing only 1.65 kg (3.6 lbs)—the team had to accomplish some serious miniaturization. They managed to fit the whole quantum experiment package—diodes, crystals, mirrors and photon detectors—atop a 10 x 10 cm circuit board.

And they’ve achieved results. Data from the satellite, which was assembled into a paper published May 31 in the journal Physical Review Applied, shows that the experiment is creating correlated photons in space, a key first step.

“This is the first time anyone has tested this kind of quantum technology in space,” gushed Alexander Ling, team leader and assistant professor at the Centre for Quantum Technologies at the National University of Singapore.

Future experiments aim to produce fully entangled photons in space, and then graduate to transmitting these entangled quanta to Earth or to other satellites. A full quantum network is envisioned to consist of a flotilla of quantum satellites and a series of ground-based arrays.

As a beneficial aside, the satellites will also advance pure quantum research, by permitting scientists to conduct quantum experiments on a grander stage.

“We are reaching the limits of how precisely we can test quantum theory on Earth,” explains study coauthor Dr. Daniel Oi of the University of Strathclyde.

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