Nuclear fusion. The dream of generating clean energy by recreating a tiny piece of the Sun here on Earth.

What images pop into your head when you think about the technology? Giant magnets? Some sort of reactor? Incredibly hot temperatures?

Fusion = Data Exchange?

Here’s something you won’t necessarily be thinking about: it turns out the future of fusion might depend on whether computers can exchange data quickly and predictably enough to keep fusion plasma stable in real time.

That was the beginning of a recent joint research project between NTT and Japan’s National Institutes for Quantum Science and Technology (QST). Together, the two partners have been able to demonstrate ultra-high-frequency communications designed for real-time plasma prediction and control inside JT-60SA, the world’s largest superconducting tokamak plasma experimental device.

All About Tokamaks

A tokamak is a doughnut-shaped fusion reactor that uses magnets to control plasma. Inside the reactor, superheated plasma tends to be restless, constantly threatening to shift and destabilize. Think about trying to balance a pencil on your fingertip while riding a skateboard; controlling a tokamak is a bit like that. Sensors have to track the plasma continuously, computers have to calculate corrective actions, and then magnetic systems have to respond almost immediately. It’s a control loop that repeats over and over at mind-boggling speeds.

When they eventually move from being research projects to a practical reality, future high-pressure fusion systems may require this entire cycle, measurement, communication, calculation, and response, to take place in under 100 microseconds. In other words, in under one ten-thousandth of a second. Ordinary networks were never designed to handle that level of performance.

One Ten-Thousandth of a Second

On the regular internet that we all use, who really cares about minor delays? A video might buffer for a split second, a webpage sometimes takes an extra moment to load. It’s fine. But fusion control systems are very different. If crucial data arrives late, even by a tiny amount, the reactor may be responding to a plasma state that has already changed.

Let’s consider everything that makes up a single control cycle. First, data from the reactor’s sensors is gathered and transmitted to control computers, which calculate how the plasma is behaving and make a judgment on whether corrective action is needed. New instructions must then travel back across the network to the magnetic systems surrounding the reactor. The entire sequence has to run repeatedly, thousands of times every second, while remaining stable and synchronized.

Jitter is Bad

NTT and QST researchers believe that future high-pressure plasma control will need stable and highly predictable data sharing below the 100-microsecond threshold. And it’s not just a question of raw speed; very small fluctuations in transmission timing, or jitter, have the potential to be a real problem in real-time control environments.

With that in mind, NTT has developed what it calls “ultra-high-frequency deterministic communication technology,” which is designed to reduce communication delays and minimize timing variations between connected control computers.

NTT and QST tested the technology within JT-60SA’s real-time control network, linking two computing systems separated by roughly 400 meters. They then simulated the entire plasma-control sequence end-to-end, including data collection, network transmission, control calculations, and the return of control instructions.

It worked. The team was able to successfully demonstrate stable data sharing below the 100-microsecond benchmark.

Part of their research focused on the repetitive rhythm of the reactor itself. Because many control operations occur in fixed cycles, the communication system could be optimized around that pattern. The project also explored technologies connected to NTT’s IOWN (Innovative Optical and Wireless Network) initiative, including methods intended to reduce network timing fluctuations.

Potential Beyond Fusion

Making it possible for computers to talk to each other incredibly quickly and without jitter could help to make the promise of nuclear fusion a reality. But even beyond fusion, there are a multitude of industries that could benefit from NTT’s work. Advanced robotics, industrial automation, remote-control systems, and other forms of real-time infrastructure are depending more and more on distributed computers reacting within extremely narrow timing windows. NTT is working to make that possible.

Innovating a Sustainable Future for People and Planet

For further information, please see this link:
https://group.ntt/en/newsrelease/2026/03/25/260325a.html

If you have any questions on the content of this article, please contact:

Public Relations
NTT Information Network Laboratory Group
https://tools.group.ntt/en/news/contact/index.php

Daniel O'Connor

Daniel O'Connor joined the NTT Group in 1999 when he began work as the Public Relations Manager of NTT Europe. While in London, he liaised with the local press, created the company's intranet site, wrote technical copy for industry magazines and managed exhibition stands from initial design to finished displays.

Later seconded to the headquarters of NTT Communications in Tokyo, he contributed to the company's first-ever winning of global telecoms awards and the digitalisation of internal company information exchange.

Since 2015 Daniel has created content for the Group's Global Leadership Institute, the One NTT Network and is currently working with NTT R&D teams to grow public understanding of the cutting-edge research undertaken by the NTT Group.