Quantum cryptography record broken

Scientists have reported an important speed breakthrough which brings closer the day when quantum encryption becomes a usable part of communications security.

The National Institute of Standards and Technology (NIST), a U.S. government agency, has reported that it has managed to shift quantum-encrypted information at a "raw" throughput of 4 million bits per second across a 1 km-long fiber link.

This is at least twice NIST's previous record, which has been rising since the agency announced it had broken the 1 million bits per second barrier in May 2004.

At such transfer rates, it becomes practical to use quantum key distribution (QKD) cryptography to secure a video stream.

"This is all part of our effort to build a prototype high-speed quantum network in our lab," said NIST's Xiao Tang. "When it is completed, we will be able to view QKD-secured video signals sent by two cameras at different locations. Such a system becomes a QKD-secured surveillance network."

Despite sounding to non-initiates like a branch of mathematical magic, the benefit of quantum key distribution in communications is really the 100 percent certainty it offers that data has not been intercepted or tampered with as it moves between two points.

Anyone attempting to decrypt a photonic data stream encoded using such a system will -- as predicted by Heisenberg's oft-quoted uncertainty principle -- inevitably alter the state of the photons in a way that can be detected. This introduces a degree of verifiability impossible in conventional electromechanical encryption systems.

The agency reckons its test-bed demonstration will pave the way for the technology's use in specific applications such as military data transfer, or the transmission of sensitive financial and health-care information.

Despite the upbeat atmosphere, there is a way to go for QKD. The trade-off is still speed relative to distance, which at 1 km for the stated throughput is still too short a distance to have many practical applications. As NIST admits, other labs have managed further distances but at the cost of cutting data rates.

In 2003, a collaboration between a number of Japanese companies achieved distances of up to 100 km in tests.

In the U.K., the Cambridge Research Laboratory has demonstrated a working commercial system running at 25 kilobits per second over a distance of 122 km.

Join the newsletter!


Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

John E. Dunn

Show Comments

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Jack Jeffries


As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr


The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?