Singapore-built quantum satellite device tests technology for global quantum network


A quantum node device that might pave the way for a future space-based quantum Internet has been successfully tested for the first time on board a small satellite.


The device, called SPEQS (or Small Photon-Entangling Quantum System)was developed by researchers from NUS’ Centre for Quantum Technologies (CQT) and the University of Strathclyde, United Kingdom. It contains technology for creating correlated photons, which are a precursor for the better known entangled photons that share properties across large distances.


CQT team leader Prof Alexander LING said, "This is the first time anyone has tested this kind of quantum technology in space."


The whole SPEQS device fits into a nanosatellite the size of a shoe box. It contains a BluRay laser, set of crystals, mirrors and photon detectors mounted on a printed circuit board 10 cm by 10cm in size. All this serves to split photons in two and measure their properties.


The satellite itself was also built by NUS researchers and students. Called Galassia, it launched in December 2015 and carries a payload to measure atmospheric properties above Singapore as well as the quantum device.


In the future, systems such as SPEQS could create entangled photons and use them to communicate across large distances through quantum networks consisting of ground-based and space-based nodes. Such a network could connect powerful quantum computers and create secure keys for secret messaging.


Quantum networks currently exist, but are considerably limited. Distance is a major obstacle in sharing information through entangled photons. Prof Ling's team aims to solve the distance limit.The hope is that space-based nodes will extend such networks’ reach beyond the few hundred kilometres achieved on the ground.


The researchers plan to soon launch a system producing actual entangled photons. They will follow up with satellites that would attempt to beam entangled photons to Earth and other satellites to connect points on opposite sides of the planet.


Prof Artur EKERT, Director of CQT, said, "Alex and his team are taking entanglement to a new level. Their experiments will pave the road to secure quantum communication and distributed quantum computation on a global scale. I am happy to see that Singapore is one of the world leaders in this area."


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Researchers at NUS and University of Strathclyde, UK, launched a satellite that tests technology for a global quantum network. This image combines a photograph of the quantum device with an artist's illustration of nanosatellites establishing a space-based quantum network. (Photo Credit: CQT, NUS)


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This image shows the creation of entangled photons in a table-top experiment (Photo Credit: CQT, NUS)


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A three-dimensional model showing the inner components of SPEQS (Photo Credit: CQT, NUS)



 Adapted from the Centre for Quantum Technologies (CQT)