Quantum Leap in Spectroscopy: New Technique Doubles Sensitivity

An international team of engineers and physicists has unveiled a groundbreaking technique that harnesses quantum light to enhance the performance of spectroscopy. This new method allows for infrared electric field measurements that are twice as sensitive as previous techniques, paving the way for advancements in security and medical diagnostics.

Time-domain spectroscopy, the current standard, relies on ultra-short laser pulses that interact with material samples. This process enables detailed analysis of a material’s molecular structure over time. Notably, recent research by Nobel Prize winner Ferenc Krausz’s team highlighted its potential in detecting early signs of diseases like cancer in blood samples.

However, traditional time-domain spectroscopy faces limitations due to the noise inherent in classical light sources, known as ‘shot noise’. This noise can obscure important signals, hindering the ability to gather further information about a sample’s composition.

The new technique, detailed in a paper published in Science Advances, uses pairs of laser pulses linked through quantum mechanics to probe infrared fields. While both beams experience shot noise, the noise patterns mirror each other. By subtracting the measurements from one beam to the other, hidden signals emerge, allowing for more sensitive readings. The researchers claim their method reduces noise by half compared to classical light, effectively doubling sensitivity.

Professor Matteo Clerici from the University of Glasgow’s James Watt School of Engineering, who led the study, expressed optimism about future applications. He stated, “In time, this technique could help us better understand material composition, detect contaminants, or identify dangerous substances like explosives in the air, as well as monitor disease markers in blood samples.”

The research team, which included Glasgow PhD students Dionysis Adamou and Lennart Hirsch, is eager to explore further enhancements. Future work may involve adapting techniques from gravitational wave detectors to boost sensitivity even more.

Collaborators from Loughborough University and the University of Strathclyde contributed to this advancement. The paper titled “Quantum-enhanced time-domain spectroscopy” is now available in Science Advances. The project received support from various funding bodies, including Innovate UK and the Royal Academy of Engineering, underscoring the significance of this research in advancing scientific understanding and practical applications.