| Jun 17, 2026 |
New quantum experiment overcomes major obstacle in search for dark matter and gravitational waves
Pairing atom-based sensors cancels overwhelming laser noise, revealing faint signals that future detectors could use to probe hidden cosmic phenomena.
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(Nanowerk News) A prototype quantum sensor developed by researchers at Imperial has demonstrated, for the first time, that a key principle behind next-generation quantum detectors can work under realistic conditions.
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The study shows how comparing two long-baseline atom interferometers, instruments that use lasers to precisely measure the behaviour of atoms, allows experimental noise to be effectively cancelled.
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This enables signals to be recovered even when individual measurements are overwhelmed, and opens the door to searches for gravitational waves from the early universe and signatures of exotic forms of dark matter.
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The work forms part of the Atom Interferometer Observatory and Network (AION) collaboration. Led by Imperial, AION brings together researchers from institutions across the UK to develop next-generation quantum sensing technologies.
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This research was published in Nature ("A prototype differential atom interferometer for fundamental physics").
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| Polarisation of blue laser light being adjusted before cooling atoms to near absolute zero. (Image: Dr Thomas Walker)
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Cancelling noise in quantum measurements
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Understanding what the Universe is made of and identifying new sources of gravitational waves remain major challenges in modern physics.
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Both problems require measuring extremely small signals that can easily be lost in background noise. Finding reliable ways to detect them is essential for exploring parts of the Universe that current experiments cannot access.
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Long-baseline atom interferometers are emerging as one of the most promising tools for this. They work by using lasers to split clouds of atoms and then bring them back together, allowing tiny changes in their motion to be measured with extreme precision.
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These experiments rely on comparing the behaviour of two clouds of atoms held at different locations and interrogated by the same laser. Any difference between the two could point to previously hidden signals, for example the presence of a dark matter field.
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However, the technique faces a major challenge. The laser used to control the experiment produces phase noise that is far greater than the signals researchers are trying to measure. Left uncorrected, this noise completely obscures these effects.
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To overcome this, scientists have proposed a differential approach, comparing two interferometers so that shared noise cancels out. This method underpins plans for next-generation detectors, but had previously not been demonstrated under realistic conditions.
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Speaking about the significance of the advance, Dr Charles Baynham, co-lead of the Ultracold Strontium Laboratory at Imperial College London, said “We’ve known for a long time that quantum sensors can help us understand the universe, but it’s only recently that it’s become possible to build them with the resolution needed.
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We’re immensely proud of our team’s efforts to make these sensors a reality – I can’t wait for the day when signals from an atom are telling us about a black hole that merged millions of years ago.”
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Testing the approach
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In the new study, researchers set out to test this principle experimentally.
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In the Imperial Ultracold Strontium Laboratory, they built a tabletop prototype with two macroscopically separated clouds of ultracold strontium-87, interrogated by a single ultrastable clock laser.
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The setup was designed to mimic the conditions expected in much larger future experiments, where controlling noise becomes increasingly difficult.
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To push the method to its limits, the team deliberately introduced large amounts of additional phase noise into the system - far more than clock lasers naturally produce - to simulate the conditions expected in long-baseline detectors.
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Individually, each interferometer became unusable, with its signal obscured by noise. The interference patterns that normally allow measurements to be made were effectively erased.
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However, when the two interferometers were compared, a clear signal could still be recovered. Even though each individual measurement appeared random, the correlation between them revealed the underlying behaviour of the system. The combined measurement operates at the fundamental limit set by quantum physics, demonstrating that laser noise cancellation works as required.
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The scientists then went a step further, introducing an additional oscillating signal into the system, similar to what might be produced by a passing gravitational wave or a dark matter field. This signal could still be detected clearly, even under conditions where neither interferometer alone contained usable information.
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| Simulated black hole mergers in the observable Universe, with projected sensitivities of existing and proposed gravitational wave detectors. The new class of atom-based sensors pioneered in this work (AION/ AEDGE) may help us see Intermediate Mass Black Holes (IMBHs) that played a pivotal role in our galaxy’s formation. (Image: ICL)
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Towards next-generation detectors
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The results provide the first experimental validation of a key principle underlying long-baseline atom interferometers, helping to resolve a central challenge in their design.
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Within the AION programme, researchers are developing the technologies needed to scale up these systems to experiments capable of probing new regions of the Universe.
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AION also forms part of a wider international programme that includes close partnerships with the MAGIS effort at Fermilab and associated US institutions, helping to advance large-scale atom interferometers for fundamental physics.
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This includes proposals such as the Atom Interferometry CERN Experiment (AICE), which would apply similar techniques over much longer distances. If realised, AICE would represent a new direction for CERN, applying quantum sensing to fundamental physics at scale. Such facilities could also rank among the largest quantum experiments of their kind.
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Dr Richard Hobson, co-lead of the Ultracold Strontium Laboratory at Imperial said "We have taken some of the most precise instruments ever built—atomic clocks and atom interferometers—and shown that they can be repurposed to open entirely new windows onto the invisible parts of our Universe.
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Our current experiment is just a prototype, but scaling it to a full-scale facility at laboratories such as CERN or Fermilab will allow us to tackle some of the deepest mysteries in physics, including the nature of dark matter."
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Imperial researchers are currently developing plans for these systems as part of an international effort to build a new generation of quantum sensors. In future, these detectors could explore previously inaccessible gravitational-wave frequency bands and search for new forms of matter, opening a previously unexplored window in the Universe.
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Professor Oliver Buchmueller, Principal Investigator of the AION collaboration at Imperial, added “This work marks an important milestone towards future large-scale quantum sensors for fundamental physics. It demonstrates, under realistic experimental conditions, a key technique relevant for next-generation atom interferometer facilities currently under development internationally, including MAGIS at Fermilab and the proposed AICE facility at CERN.”
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