Thanks to a collaboration between researchers at the Quantum Communications Hub and their German colleagues, the world is taking a further step towards secure conference calls, allowing four parties to have a conversation with quantum security simultaneously.
The demonstration, led by Hub researchers based at Heriot-Watt University and published in Scientists progress, is a welcome step forward, given the global reliance on remote collaborative work, including conference calls, since the onset of the C19 pandemic.
There have been reports of significant escalation of cyber attacks on popular teleconferencing platforms over the past year. This advance in secure quantum communications could lead to conference calls with inherent un-hackable security measures underpinned by the principles of quantum physics.
Lead author Professor Alessandro Fedrizzi, who led the Heriot-Watt team, said: âWe have known for a long time that quantum entanglement, which Albert Einstein called ‘spooky action at a distance’ can be used to distribute secure keys. Our work is the first example where this has been achieved via a “scary action” between multiple users at the same time – something that a future quantum internet will be able to exploit. “
Secure communications rely on the sharing of cryptographic keys. Keys used in most systems are relatively short and therefore can be compromised by hackers, and the process of key distribution is increasingly threatened by rapidly evolving quantum computers. These growing threats to data security require new secure methods of key distribution.
A mature quantum technology called Quantum Key Distribution (QKD), first deployed in this demonstration in a network scenario, harnesses the properties of quantum physics to facilitate guaranteed secure distribution of cryptographic keys.
QKD has been used to secure communications for more than three decades, facilitating communications over 400 km over terrestrial fiber optics and even recently in space. facilitate secure conversations between multiple users.
The system demonstrated by the team here uses a key property of quantum physics, entanglement, which is the property of quantum physics that gives correlations – stronger than any we are familiar with in everyday life – between two or more quantum systems, even when these are separated by large distances.
By exploiting the multi-party entanglement, the team was able to share keys between the four parties simultaneously, through a process known as ‘quantum conference key agreement’, overcoming the limitations of traditional QKD systems for sharing keys. between only two users, and allowing the first quantum conference call to take place with an image of a Cheshire cat shared between the four parties, separated by up to 50 km of optical fiber.
Entanglement-based quantum networks are just one part of a larger program of work that the Quantum Communications Hub is undertaking to provide future secure quantum networks.
The technology demonstrated here has the potential to significantly reduce resource costs for conference calls in quantum networks compared to standard two-party QKD methods. This is one of the first examples of the expected benefits of a future quantum internet, which is expected to provide entanglement to a system of globally distributed nodes.
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