Researchers at University College Dublin and international collaborators have just published a detailed and accessible guide that aims to translate theoretical ideas into practical devices for quantum enhanced sensing technologies.
Conventional sensors have enabled technologies from global positioning systems to satellite imaging. Quantum systems, however, provide the absolute best precision allowable by the laws of physics.
The challenge, however, is that quantum devices are often fragile. A promising theoretical avenue for designing quantum sensors not hindered by this fragility is called ‘critical quantum sensing.’
The idea behind ‘critical quantum sensing’ is to use a quantum system’s tipping point as a measurement tool: just as water suddenly freezes into ice, the system undergoes a sharp physical change that can make tiny signals much easier to detect.
UCD researchers working in the emerging scientific field of ‘critical quantum metrology’ introduce these complex theoretical ideas to a broad audience and explain how to apply them with existing experimental platforms through their tutorial, which has been published today in PRX Quantum.
Real-World Impact for Society and Industry
Harnessing these quantum phase transitions has potential real-world benefits. Lead author Dr George Mihailescu, a postdoctoral researcher in UCD School of Physics and UCD Centre for Quantum Engineering, Science and Technology (C-QuEST), said: "Quantum sensors operate at the edge of what the laws of physics allow, and they are already producing real results" – including their application in major international research efforts such as the LIGO experiment for detecting gravitational waves.
"By exploiting even more exotic quantum effects we can push sensing into regimes that are currently beyond reach," he said.
Potential areas that could translate the research to impact:

• Advanced Everyday Sensors: Ultra-precise quantum sensors could significantly improve technologies deeply embedded in our daily lives, such as navigational tools and environmental monitoring systems.
• Medical Diagnostics: The heightened sensitivity of critical quantum sensors could lead to breakthroughs in medical imaging and diagnostics.
• Scientific Discovery: This technology can push measurement capabilities far beyond classical limits, benefiting fields ranging from fundamental physics – such as detecting gravitational waves – to advanced astronomical imaging.
• Robustness against Noise: By utilising the collective physical behaviours that emerge naturally near quantum phase transitions, the tech industry can create advanced sensors that are easier to scale up and much more resilient against technical noise and decoherence.

The project is in collaboration with Prof Gabriele De Chiara (Queen's University Belfast and Universitat Autònoma de Barcelona) and jointly funded by UKRI and Research Ireland-Taighde Eireann, under grant number 24/EPSRC/4121.

Co-authors on the paper are Uesli Alushi and Roberto Di Candia, Aalto University, Finland; Simone Felicetti, Institute for Complex Systems and Sapienza University, Italy; and Karol Gietka, Universität Innsbruck, Austria.

About UCD C-QuEST

UCD Centre for Quantum Engineering, Science, and Technology brings together expertise in quantum research from across the University in the Schools of Physics, Mathematics & Statistics, Engineering, and Computer Science. With over 25 permanent academic staff members, UCD C-QuEST is the leading quantum research hub in the Nation's Capital, providing a gateway for industrial partners and spin-out companies.
Learn more at https://www.ucd.ie/quantum/aboutus/