Quantum Sensing Methods Promise to Improve Greenhouse Gas Detection

Insider Summary

• Quantum technology is an important tool for efforts to reduce greenhouse gases. This new technique can detect and characterize molecules with greater precision.
• This technique can also be used for medical diagnostics and industrial processes.
• The UK National Quantum Technology Program, the EPSRC Doctoral Training Center in Quantum Engineering, and the European Research Council supported the research.
• Image: Optical frequency comb probe gas molecule illustration, credit Alex Belsley

PRESS RELEASE — An innovative technique for detecting and characterizing molecules with greater precision has been proposed, paving the way for significant advances in environmental monitoring, medical diagnostics, and industrial processes.

The new quantum sensing method, proposed by University of Bristol physicists, builds on the work of 2005 Nobel physics laureates John Hall and Theodor Hänsch who developed a frequency comb technique to accurately measure optical frequencies. Frequency combs are used in many fields of science and industry to characterize materials based on their unique way of absorbing light.

However, the precision of optical comb spectroscopy is limited by the fundamental noise levels present in all lasers and other classical light sources. A noise-reduced quantum state called ‘squeezed light’ overcomes this limitation and has been exploited to increase the sensitivity of gravitational wave detectors.

In a paper published in Physical Review LetterSqueezed light was shown to significantly suppress noise over a wide range of comb frequencies used to investigate absorbent molecules.

Author Alex Belsley, PhD student of Quantum Engineering, said: “This work proposes a new method for monitoring gas species on site and with high precision. Quantum gains in sensing can be realized today and I am excited for the transformative impact of quantum-enhanced sensors on our society for years to come.

This new approach has the potential to achieve a more than tenfold increase in detection limits. As well as allowing a wide range of gases to be characterized at very low concentrations, it can also determine important properties such as temperature and pressure with high sensitivity.

Professor Jonathan Matthews, co-director of the Quantum Engineering Technology Labs at the University of Bristol and PhD advisor to Alex Belsley, said: “Better sensors are important for our future. Health care, manufacturing, environmental monitoring, and the new science itself are all benefiting from advances in how we measure physical properties. Alex’s work shows how squeezed light can enhance frequency comb spectroscopy – the next step is to explore this further with lab experiments.”

This research is supported with funding from the UK National Quantum Technology Programme, the EPSRC Doctoral Training Center in Quantum Engineering, and the European Research Council.