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Physicists Demonstrate Photo Sensing at the Ultimate Quantum Limit

An operational method for mass manufacturable photonic sensors at the quantum limit has been found by a Bristol-led team of physicists. This development leads the way for hands-on applications, like cancer detection and monitoring greenhouse gases.

Physicists Demonstrate Photo Sensing at the Ultimate Quantum Limit.
Photonic chip with a micro ring resonator nanofabricated in a commercial foundry. Image Credit: Joel Tasker, QET Labs

Sensors are an inextricable part of the daily routine. They offer crucial information for contemporary healthcare, security, and environmental monitoring, even if they go unnoticed. In modern cars, there are over a hundred sensors, and this number is only going to grow.

Quantum sensing has the potential to revolutionize today’s sensors, dramatically improving their performance. In every field of science and technology, including ordinary routine, more accurate, quicker, and trustworthy measurements of physical quantities can have a transformational influence.

Nevertheless, several quantum sensing systems rely on difficult-to-make and hard-to-detect unique entangled or compressed states of light or matter. This is a significant impediment to fully harnessing the potential of quantum-limited sensors and implementing them in real-world applications.

A team of physicists from the Universities of Bristol, Bath, and Warwick has demonstrated that high precision measurements of essential physical characteristics can be made without the need for advanced quantum states of light and detection systems in a study published in Physical Review Letters.

The utilization of ring resonators, which are small racetrack devices that channel light in a loop and enhance its engagement with the material under examination, is the key to this success. Ring resonators can be mass-produced in the same way chips in computers and cellphones are.

We are one step closer to all integrated photonic sensors operating at the limits of detection imposed by quantum mechanics.

Alex Belsley, Study Lead Author and PhD Student, Quantum Engineering Technology Labs (QET Labs), University of Bristol

This technique, which detects changes in absorption or refractive index, can be used to identify and classify a wide range of materials and biological samples, with applications ranging from greenhouse gas monitoring to cancer diagnosis.

We are really excited by the opportunities this result enables: we now know how to use mass manufacturable processes to engineer chip scale photonic sensors that operate at the quantum limit.

Jonathan Matthews, Co-Director, Quantum Engineering Technology Labs, and Associate Professor, University of Bristol

Journal Reference:

Belsley, A., et al. (2022) Advantage of Coherent States in Ring Resonators over Any Quantum Probe Single-Pass Absorption Estimation Strategy. Physical Review Letters. doi:10.1103/PhysRevLett.128.230501.


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