Way towards safer online communication

A unique prototype which could transform how we communicate online.


Quantum communication is rapidly gaining popularity due to its high security and technological maturity. However, most implementations are limited to just two communicating parties (users). Quantum communication networks aim to connect a multitude of users.

Quantum communication networks present a revolutionary step in the field of quantum communication.

Scientists at the University of Bristol have created a unique prototype understood to be the largest-ever quantum network of its kind. It could secure people’s online communication, particularly in these internet-led times, accelerated by the COVID-19 pandemic.

The prototype has been developed using a technique that controls the laws of physics. The method makes messages completely safe from interception while also overcoming significant challenges.

Lead author Dr. Siddarth Joshi, who headed the project at the university’s Quantum Engineering Technology (QET) Labs, said: “This represents a massive breakthrough and makes the quantum internet a much more realistic proposition. Until now, building a quantum network has entailed huge cost, time, and resource and often compromises on its security, which defeats the whole purpose.”

“Our solution is scalable, relatively cheap, and, most important of all, impregnable. That means it’s an exciting game-changer and paves the way for much more rapid development and widespread rollout of this technology.”

The group’s quantum technique applies a magical principle, called entanglement, which Albert Einstein depicted as ‘creepy action at a distance.’ It exploits the power of two distinct particles placed in separate locations, possibly a large number of miles apart, to emulate one another simultaneously. This process presents far more prominent open doors for quantum computers, sensors, and information processing.

Dr. Joshi said“Instead of having to replicate the whole communication system, this latest methodology, called multiplexing, splits the light particles, emitted by a single system so that they can be received by multiple users efficiently.”

Using just eight receiver boxes, scientists created a network for eight users. As the user numbers grow, the logistics become increasingly unviable – for instance, 100 users would take 9,900 receiver boxes.

Scientists connected receiver boxes at different locations using optical fibers. The aim was to determine its functionality across the distance. Scientists tested the ability to transmit messages via quantum communication.

Despite being completely secure, the technique can move quickly and easily without requiring maximum hardware. It also features traffic management, delivering better network control, which allows, for instance, individual users to be prioritized with a faster connection.

The research received funding from the Quantum Communications Hubs of the Engineering and Physical Science Research Council (EPSRC), Ministry of Science and Education (MSE) of Croatia, and the Austrian Research Promotion Agency (FFG).

Collaborating institutions with the University of Bristol are the University of Leeds, Croatia’s Ruder Boskovic Institute (RBI) in Zagreb, Austria’s Institute for Quantum Optics and Quantum Information (IQOQI) in Vienna, and China’s National University of Defence Technology (NUDT) in Changsha.

Journal Reference:
  1. Siddarth Koduru Joshi et al. A trusted node–free eight-user metropolitan quantum communication network. DOI: 10.1126/sciadv.aba0959