How quantum science can illuminate the brain

The brain is the least understood organ of the human body. It is functionally complex and hard to access, encased in the skull and behind a blood-brain barrier. We can, however, track the electrical currents that fire neuronal communication, as they produce magnetic fields detectable beyond the scalp. But the conventional imaging systems, including magnetoencephalography utilising superconducting quantum interference devices (SQUIDs), are clunky and impractical.

Dr Anna Kowalczyk, Assistant Professor at the University of Birmingham’s Centre for Human Brain Health, and colleagues employ magnetoencephalography to detect the minute magnetic fields generated by neural activity by using optically pumped magnetometers (OPMs). These are agile, simple and easy-to-use sensors that harness atom-light interactions to measure magnetic fields through Larmor precession — the rotation of spinning atoms in a magnetic field.

When a laser light source is applied as the atoms spin, the rotation is imprinted on the light and can be measured. “The process uses rubidium atoms in a small cell, where laser light interaction enables precise magnetic field measurements,” explained Kowalczyk. This offers several advantages. The sensors can be miniaturized and placed directly on the head, accommodating both adult and pediatric imaging. OPM-based sensors are more cost-effective, robust, and maintenance-light than traditional methods.

A background in quantum physics is proving instructive for brain imaging, thanks to its reliance on laser physics and light-matter interaction. “We mastered the technique of working with cold atoms and decided to use it in healthcare,” argues Professor Giovanni Barontini, Professor of Physics at the University of Birmingham.

“We have expertise in the quantum field. We don’t just implement commercial sensors, we develop bespoke solutions for specific neuroscience applications,” he added. “We make our sensors and give them new flavour,” noted Kowalczyk. This customization enables integration with other neurological research methods, expanding the possibilities for brain study.

One innovation involves combining their sensors with Transcranial Magnetic Stimulation (TMS), a non-invasive technique that delivers magnetic pulses to stimulate or suppress brain activity. Kowalczyk says the existing process lacks refinement. “Stimulation is blind because the operator does not have control over the device; they hope that they stimulate the area of the brain they are aiming for”.

The team's enhanced sensors provide real-time feedback during stimulation, allowing operators to target specific brain regions accurately. This enables immediate recording of brain signals following stimulation, offering unprecedented insight into neural responses.

Understanding the misfiring mind

The researchers' work extends to brain connectivity. By combining their sensors with TMS, they can study how brain regions interact, revealing crucial information about hemispheric symmetry and neural network connections—insights previously unknown due to interference from traditional magnetic field measurements.

“When we stimulate one part of the brain, we want to measure what happens in other parts. This cannot be done with any other technique because the strength of the magnetic field destroys every other kind of sensor. We know the physics behind our sensors, and we can make them work with the magnetic field,” said Barontini.

The clinical applications span various neurological conditions. TMS is already an approved treatment for obsessive-compulsive disorder, migraines, depression, and smoking cessation when conventional treatments fail. Research is underway to identify its diagnostic and therapeutic efficacy for other neuropsychiatric conditions.

The team's enhanced sensing capabilities could expand these applications by providing detailed information about connectivity changes in various brain disorders, which could help diagnose and treat conditions ranging from Alzheimer's disease to epilepsy. “We can measure connectivity when a healthy brain is engaged in various tasks, and then we can see how it changes when there is a disorder,” explained Kowalczyk. “In the long term, this measurement system can be a diagnostic tool for various conditions”, she added.

Future developments include integrating Functional Near Infrared Spectroscopy (fNIRS) with their sensor technology. This measures the refraction of near-infrared light that is directed into the brain, and this measurement reveals important information about blood oxygen levels, oxygen utilization and cerebral blood flow. “This method can also measure brain metabolism and could provide supplementary information alongside diagnostics,” explained Kowalczyk. “We would like to develop hybridized sensors with two modalities that can, for example, help diagnose mild traumatic brain injury. Our goal is to make better tools for neuroscientists.”

The fundamental research imperative

In 2025, the field of quantum science and technology celebrates 100 years of existence, and is projected to create trillions of dollars as breakthroughs accelerate over the coming decades. Six quantum technology hubs in the UK have benefited from government investment due to their market potential, but fundamental research faces funding constraints.

Barontini emphasizes the critical importance of supporting core research alongside technological development. “The current funding landscape favours high technology readiness level (TRL) projects—those closer to market application—over low TRL fundamental research”. But true technological advances come from breakthroughs in our fundamental understanding. Kowalczyk advocates for continued support of basic research, noting opportunities for further improvements in technologies like OPMs. “We could still do much more research to improve the OPMs, for example. We could develop new methods to make our sensors truly quantum, but that all has to happen in the labs.”

The team’s approach shows how fundamental physics can drive practical medical applications. As brain imaging technology evolves, supporting both basic research and applied development is crucial for advancing our understanding of neurological conditions and improving patient care.

Pioneering work in the Atomic Quantum Systems group reveals the intersection of quantum physics and neuroscience – and the importance of fundamental research to advance our understanding of science and health.