Quantum entanglement demonstrated on tiny CubeSat in orbit

Researchers have managed to demonstrate quantum entanglement on a small satellite orbiting Earth. The team developed a miniaturized device that can produce pairs of photons that are inextricably linked, which could help launch a fast and secure quantum internet.

Quantum entanglement is the eerie phenomenon where two particles can become so entwined that changing the properties of one will affect the other – no matter how far apart they are. In theory, they could be on opposite sides of the universe and still communicate instantaneously.

But that raises some uneasy physics questions. After all, nothing is supposed to be able to travel faster than light, yet that information apparently does. The idea so unnerved Einstein that he referred to it as “spooky action at a distance.”

As counterintuitive as it is though, quantum entanglement has been reliably observed in experiments for decades. And now, researchers at the National University of Singapore have squeezed the mechanism down even further.

The new mini-satellite is named SpooQy-1, no doubt a reference to Einstein’s famous quote on the subject. It carries a device that can produce pairs of photons that are quantum entangled, by shining a blue laser diode onto non-linear crystals.

The miniaturized device that produces pairs of entangled photons, onboard a CubeSat called SpooQy-1
The miniaturized device that produces pairs of entangled photons, onboard a CubeSat called SpooQy-1

Centre for Quantum Technologies, National University of Singapore

SpooQy-1 isn’t the first quantum satellite – that honor belongs to China’s Micius – but it is by far the smallest. Micius is a full-sized satellite, weighing 600 kg (1,323 lb). Meanwhile, SpooQy-1 is a CubeSat, weighing less than 2.6 kg (5.7 lb) and measuring just 20 x 10 cm (7.9 x 3.9 in).

Micius was great for showing that quantum communication via satellite is viable, even managing to repeatedly break quantum teleportation distance records by transmitting entangled photons over thousands of kilometers.

But in order to make a truly global quantum internet, a network of quantum satellites would be needed. Ideally they’d be smaller and cheaper to make and launch, and that’s where SpooQy-1 comes in.

The team designed and tested the CubeSat’s instrument to make sure that it could reliably produce entangled pairs of photons, while being smaller, lighter and more energy efficient. Importantly, it also had to be able to withstand the extremes of a space launch.

Sure enough, SpooQy-1 was able to continue producing entangled photon pairs after temperature swings between -10 °C and 40 °C (14 °F and 104 °F).

“In the future, our system could be part of a global quantum network transmitting quantum signals to receivers on Earth or on other spacecraft,” says Aitor Villar, lead author of the study. “These signals could be used to implement any type of quantum communications application, from quantum key distribution for extremely secure data transmission to quantum teleportation, where information is transferred by replicating the state of a quantum system from a distance.”

The research was published in the journal Optica.

Source: The Optical Society

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