Researchers from the University of Liverpool’s Particle Physics frontier have contributed to a major advance in quantum sensing that could help pave the way for future searches for ultralight dark matter and gravitational waves.
The new study, published in Nature, reports the successful demonstration of a prototype differential atom interferometer developed by the Atom Interferometer Observatory and Network (AION) collaboration. The experiment showed that signals can be recovered even when individual measurements are overwhelmed by laser noise, addressing a key challenge for the long-baseline quantum sensors needed to probe some of the most fundamental questions in physics.
Atom interferometers use lasers to control and measure the quantum behaviour of clouds of ultracold atoms. In future, large-scale versions of these instruments could search for tiny effects caused by passing gravitational waves or by hypothetical ultralight dark matter fields. The new prototype used fermionic strontium atoms and demonstrated that comparing two atom interferometers can cancel out shared noise while preserving an underlying and time-varying signal.
The results mark an important milestone for long-baseline atom interferometry, experimentally validating a principle that will be essential for scaling up the technology to larger detectors. Although the prototype baseline was only on the millimetre scale, the work demonstrates that the underlying approach is suitable for future experiments with much longer baselines.
Liverpool’s Atom Interferometry group, led by Professor Jonathon Coleman and Dr Jonathan Tinsley in the Department of Physics, are founding members of AION and are playing a key role in broader international efforts to develop long-baseline atom interferometers with sensitivity to new physics. Liverpool acts as the UK lead for AION’s sister experiment, MAGIS-100 at Fermilab, which will offer an unprecedented 100-metre interferometer baseline, aiming to exploit the advances demonstrated here for the first time to to explore previously inaccessible parameter space for ultralight dark matter.
Liverpool researchers are also involved in proposals for future large-scale atom interferometry facilities, including the Atom Interferometry CERN Experiment (AICE) and international efforts towards kilometre-scale detectors that could bridge the gap between terrestrial and space-based gravitational-wave observatories. Liverpool's atom interferometry programme is part of the wider work in the Particle Physics Frontier and the Department of Physics towards developing quantum technologies for fundamental and applied physics, including other dark matter search experiments such as FLASH.
Professor Jonathon Coleman said:
“This is an exciting milestone for AION and for the wider field of long-baseline atom interferometry. The experiment demonstrates a key principle needed to build future quantum sensors capable of probing parts of the Universe that are currently beyond the reach of existing detectors.”
Dr Jonathan Tinsley added:
“Liverpool has been closely involved in this international effort from an early stage, and this result is an important milestone towards larger-scale experiments. Our work with AION, MAGIS-100 and other future proposed facilities is helping to develop the technologies and analysis techniques needed to realise the scientific potential of long-baseline atom interferometry, including novel searches for ultralight dark matter, mid-bandgravitational wave detection, and probing the fundamentals of quantum mechanics.”
The AION collaboration is led by Imperial College London and brings together researchers from institutions across the UK, including the University of Liverpool, King’s College London, the Universities of Birmingham, Cambridge and Oxford, and STFC Rutherford Appleton Laboratory. The programme has been supported by the Quantum Technologies for Fundamental Physics programme, a joint STFC–EPSRC initiative. The collaboration dedicates this work to the memory of the late Prof Ian Shipsey. The paper, A prototype differential atom interferometer for fundamental physics, is published in Nature, and can be read here.