Rendezvous in the Sky

Rendezvous in the Sky

Chinese scientists show the way to implement a cost-effective infrastructure for the quantum internet

China, a nation at the forefront of research and technological development, had been in the news for all the wrong reasons throughout the last one year. There was the pandemic and the blame-game, lobbying at the WHO and geopolitical implications, global powers shifting sides to safeguard domestic political interests, a complete rethinking of the global supply-chain matrix, and a rat-race to relocate electronics and manufacturing assembly units out of China.

The dust is yet to settle, and the vaccine-debate is still far from conclusion. But technological updates have again started to trickle out of R&D labs in China, and it seems that research scientists have got their priorities sorted out, as ever. The latest news releases reveal that Chinese computer scientists have already gained a grip on the latest craze for the future – quantum computing.

Researchers from Nanjing University recently demonstrated successful communication between a pair of drones flying one kilometre apart, purely through quantum technology. They were able to transmit entangled photons between the two airborne drones – named Alice and Bob – by using an onboard laser and crystal device mounted on one drone. The technique involved splitting a single photon into a pair of entangled photons using the device. One of the split photons was then transmitted to the other drone and the other one was successfully sent to a ground station. Motorized devices were installed on both the drones to ensure that the receivers and transmitters were in alignment with one another. The entire experiment was a major step in setting up an affordable infrastructure for a quantum internet by leveraging low-cost devices and available technology.

Quantum communication at a distance, by employing the entanglement property of quantum physics, was not what this experiment was trying to highlight. That has already been demonstrated by other scientists – between satellites and stationary ground stations. What the Nanjing University scientists demonstrated was fundamentally more practical; they showed that such state-of-the art communication infrastructure can be effectively set-up using much cheaper hardware – although at shorter distances as of now. Industry observers have additionally pointed out that this was the first time that such photon entanglement has been shown to work between two moving objects.

In a press interview, professor ZhendaXie from the School of Electronic Science at Nanjing University explained that “this work demonstrates the optical relayed link between mobile nodes, which we believe is an enabling technology for future free-space quantum communication with longer distance, lower loss, and broader coverage range…. Meanwhile, it provides a cost-effective new platform with extraordinary flexibility and configurability. It can be a good compensation to fill the gap between fibre and satellite quantum communication to realize a practical full-coverage quantum network in the future.”

But the benefits of such developments in quantum communication would not only be limited to setting up quantum networks. The innovation would also impact large-scale distributed quantum computation, precision timekeeping, in-depth experiments in fundamental quantum physics, and similar initiatives where traditional communication systems can cut no ice.

As a next step in the research, the Nanjing scientists are aiming to increase the scale of the mobile quantum connections, gradually building a quantum network with complex topologies. They plan to house the quantum nodes in smaller and more cost-effective drones, leading to multi-user coverage at the local-area networking level. They also hope to set up broad-area quantum coverage using unmanned aerial vehicles placed at high altitudes – because at that level there would be less scattering loss than at lower-altitude dusty air.

And looking beyond the immediate, we foresee that such ariel systems could collaborate and work in tandem with the existing fibre- and satellite-based communication systems. That could lay the true foundation for low-cost quantum coverage at a global level.

Anyone interested in the details of the Nanjing experiment can access the paper at the following URL:

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