BT adds quantum security to hollowcore fibre

BT is pretty upbeat about the possibilities of using quantum security methods to transmit data over hollowcore fibre, carrying out a trial that has implications for faster, less hackable connections.

The UK incumbent is building on previous endeavours in both hollowcore fibre and quantum security, specifically, Quantum Key Distribution (QKD). It has trialled QKD over hollowcore fibre and is claiming a world first for having done so.

“This is an exciting milestone for BT, accelerating the UK’s lead in quantum technologies that will play an important role in future communications systems globally,” said Professor Andrew Lord, Head of Optical Network Research at BT. “We’ve proven a range of benefits that can be realised by deploying hollow core fibre for quantum-secure communication. Hollow core fibre’s low latency and ability to send QKD over a single fibre with other signals is a critical advancement for the future of secure communications.”

To understand the benefits, it’s necessary first to explain the technology.

Hollowcore fibre is, as its name suggests, a fibre-optic cable with a tube of air running through the centre, rather than a solid glass core. Its main advantage is lower latency.

BT has been working with hollowcore fibre for a number of months, having partnered with Mavenir and hollowcore fibre specialist Lumenisity, a start-up out of the University of Southampton, to trial it at Adastral Park.

Quantum-secure networks have also been on its radar for some time. In October last year the telco teamed up with Toshiba to deploy a quantum-secure network linking composite R&D facility the National Composites Centre (NCC) and digital engineering research organisation the Centre for Modelling & Simulation (CFMS), both in Bristol. The following month it announced the AIRQKD trial, in which it used its QKD expertise alongside techniques for applying quantum security to mobile devices developed by UK start-ups Nu Quantum, Angoka and Duality, the goal being to test out quantum-secured communications for 5G and connected cars.

Simply put, QKD Is a way of sharing encryption keys between locations using a stream of single photons. It is described as unhackable, since by its very nature the process can detect disturbances.

That single photon channel traditionally needs it own separate fibre to avoid crosstalk, but using hollowcore fibre can mitigate crosstalk and therefore makes it possible for the same fibre to carry both the high-speed encrypted data stream and the faint quantum signal that carries the encryption key.

From a technological point of view, that’s clearly a big step forward. But we are still at the trial stage.

BT said its researchers were able to operate a QKD system, loaned to them by the EU OpenQKD project, using commercial equipment over a 6-km Lumenisity CoreSmart cable. The test demonstrated reduced latency – although the telco did not provide figures for that – and no appreciable crosstalk.

Job done. For now. It will be interesting to see where the technology goes from here.

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