Research paves way for photonic sensing at quantum limit

Sensors provide critical information essential to modern healthcare, security and environmental monitoring. Modern cars alone contain over 100 sensors and this number is set to increase.

Quantum sensing is poised to revolutionise today’s sensors and significantly boost their performance. More precise, faster and reliable measurements of physical qualities has potential to transform many aspects of technology, including in our daily lives.

However, the majority of quantum sensing schemes rely on special entangled or squeezed states of light or matter that are hard to generate and detect. This is a major obstacle to harnessing the full power of quantum-limited sensors and deploying them in real-world scenarios.

In a paper published this week, a team of physicists at Bristol, Bath and Warwick Universities demonstrated the possibility of performing high precision measurements of important physical properties without the need for sophisticated quantum states of light and detection schemes.

The key, researchers said, is through the use of ring resonators — tiny racetrack structures that guide light in a loop and maximise its interaction with the sample under the study. Ring resonators can be mass manufactured using the same process as the chips in  computers and smartphones.

“We are one step closer to all integrated photonic sensors operating at the limits of detection imposed by quantum mechanics,” said Alex Belsley, Quantum Engineering Technology Labs (QET Labs) PhD student and author of the work.

According to the team, employing the technology to sense absorption or refractive index changes could be used to identify and characterise a range of materials and biochemical samples, with topical applications from monitoring greenhouse gases to cancer detection.