It is a major milestone for all researchers working on quantum brain imaging technology because modular sensors can be scaled up, like Lego bricks.

The team, led by researchers at the University of Sussex, have also connected two sensors like Lego bricks, proving that whole-brain scanning using this method is within reach. This has not been possible with the currently commercially available quantum brain sensors from the US.

These modular devices work like play bricks in that they can be connected together. This opens up the potential for whole-brain scanning using quantum technology, and potential advances for neurodegenerative diseases like Alzheimer's.

The device uses ultra-sensitive quantum sensors to pick up these tiniest of magnetic fields to see inside the brain in order to map neural activity.

The team applied the sensors to the outside of a participant's scalp, close to the visual cortex of the brain. They asked the participant to open and close their eyes at 10-20 second intervals, and were able to detect a signal. This is a very simple action, but to see it happening inside the brain -- from the outside -- requires highly sophisticated quantum technology.

"Our quantum sensor has to be exceptionally sensitive to pick up the magnetic fields in the brain which are very weak indeed. To put it into context, the magnetic field of a brain is a trillion times lower than that of a fridge magnet," said Thomas Coussens Ph.D. student at the University of Sussex.

"Because our device is so-far unique in that it is modular -- and we've shown the modularity works by connecting two sensors together -- we now plan to scale up this project by building more sensors to turn this into an entire brain imaging system. This could provide significant advancements in detecting and delivering treatment for neurodegenerative diseases such as Alzheimer's.