A quantum discovery from researchers at the University of Strathclyde could herald significant improvements for future medical technologies across fields like biomedical imaging and spectroscopy.

Strathclyde’s scientists have found that two-photon processes, which have applications in the study of Alzheimer’s Disease and other nervous system disorders, can be strengthened by quantum light at far higher levels than previously thought possible.  

The processes normally require high-intensity light, but this can cause samples to be damaged or bleached, though it has since been demonstrated that entangled photon pairs could overcome this limitation. 

However, until now, it has been widely believed that this quantum enhancement survives only for very faint light, raising doubts about the usefulness of the approach.

With this latest study, scientists now have evidence of quantum enhancement working at light intensity levels nearly ten times higher than originally thought possible.

Researchers from Scotland, working in collaboration with Italian colleagues, made experimental and theoretical explorations of two-photon processes and compared the quantum physics results with those of an experiment using classical, non-quantum, light. 

The theoretical and experimental results were well matched, indicating that the two-photon processes driven by quantum light are more efficient than their classical counterpart, even at higher intensities where quantum enhancement has been expected to fade. 

According to Strathclyde University, the study, published in Science Advance, could pave the way for new technology which offers increased signal strengths without sacrificing quantum enhancement. 

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“We have been able to demonstrate that quantum effects can still provide an advantage well beyond the level of low intensity,” said Dr Lucia Caspani, lead researcher in the project and visiting researcher at Strathclyde’s Institute of Photonics.

“This could significantly expand the role of quantum light in applied technologies, notably within the field of biosensing. Our research could lay the groundwork for the next generation of quantum-enhanced sensing approaches.”

A previous project at Strathclyde, also led by Caspani, was awarded a grant of nearly €2 million (£1.7m) from the European Research Council in 2023 to develop a system which enables enhanced 3D imaging of a biological sample through quantum entanglement.

Set to run for five years, the QuNim, or Quantum-enhanced nonlinear imaging, project promises to overcome limitations in current imaging systems and to achieve deeper imaging than they at present allow.