The research showed that comparing two long-baseline atom interferometers, highly sensitive instruments that use lasers to track the motion of atoms, can effectively eliminate experimental noise. As a result, scientists can recover meaningful signals even when individual measurements appear completely overwhelmed.

The advance could help pave the way for future searches for gravitational waves from the early universe and possible signs of exotic forms of dark matter.

The work is part of the Atom Interferometer Observatory and Network (AION), a UK-wide collaboration led by Imperial that is developing next-generation quantum sensing technologies.

The findings were published in Nature.

Using Quantum Sensors To Explore the Universe

One of the biggest unanswered questions in physics is what the universe is made of. Scientists are also searching for new sources of gravitational waves, ripples in spacetime produced by some of the most powerful events in the cosmos.

Both goals depend on detecting incredibly faint signals that can easily disappear beneath background noise. Developing methods that can reliably separate those signals from interference is essential if researchers hope to explore regions of the universe that remain beyond the reach of current instruments.

Among the most promising tools for this task are long-baseline atom interferometers. These devices use lasers to split clouds of atoms and later recombine them, allowing researchers to measure tiny changes in atomic motion with extraordinary precision.

The technique compares two atom clouds located in different places but controlled by the same laser. Any difference between their behavior could indicate the presence of previously unseen phenomena, such as a dark matter field.

A major obstacle, however, comes from the laser itself. The phase noise generated during operation is far stronger than the signals scientists are trying to detect. Without a way to remove that noise, the desired measurements become impossible to see.

Researchers have long proposed solving this problem by comparing two interferometers and canceling out the noise they share. Although this idea forms the foundation of future detector designs, it had never before been demonstrated under realistic experimental conditions.

Discussing the significance of the achievement, 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.

"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."

Testing Quantum Noise Cancellation

To test the concept, the team built a tabletop experimental system in the Imperial Ultracold Strontium Laboratory.

The setup used two widely separated clouds of ultracold strontium-87 atoms that were measured using a single ultrastable clock laser. It was designed to replicate the conditions expected in future large-scale detectors, where noise control becomes increasingly challenging.

To create an especially demanding test, the researchers intentionally added large amounts of extra phase noise to the system, far beyond what clock lasers normally generate. The goal was to mimic the environment expected in long-baseline atom interferometers.

Under those conditions, each interferometer on its own became effectively unusable. The interference patterns needed for measurement were buried beneath the noise.

When the scientists compared the two interferometers, however, the underlying signal reappeared. Although each individual measurement looked random, the relationship between the two datasets revealed the system's true behavior. The combined result reached the fundamental limit imposed by quantum physics, confirming that the noise-canceling approach works as intended.

The team then introduced an additional oscillating signal designed to resemble the effect of a passing gravitational wave or a dark matter field.

Even in situations where neither interferometer produced useful information on its own, the added signal remained clearly detectable when both systems were analyzed together.

Toward Future Dark Matter and Gravitational Wave Detectors

The results provide the first experimental confirmation of a central principle behind long-baseline atom interferometers and address one of the most significant challenges facing their development.

Through the AION program, researchers are working to scale these technologies into larger instruments capable of exploring previously inaccessible regions of the universe.

AION is also connected to a broader international effort that includes close collaboration with the MAGIS project at Fermilab and other US institutions. Together, researchers are advancing large-scale atom interferometers designed for fundamental physics research.

One proposed future project is the Atom Interferometry CERN Experiment (AICE), which would apply similar techniques across much greater distances. If built, AICE would mark a new direction for CERN by using quantum sensing technologies to investigate fundamental physics on an unprecedented scale. It could also become one of the largest quantum experiments ever constructed.

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.

"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."

Imperial researchers are continuing to develop plans for larger systems as part of a global effort to build a new generation of quantum sensors.

In the future, these detectors could explore gravitational-wave frequencies that are currently inaccessible and search for entirely new forms of matter, providing a fresh way to study the cosmos.

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."

The AION collaboration is led by Imperial College London and includes researchers from the Universities of Birmingham, Cambridge, Liverpool Kings College, and Oxford, along with STFC Rutherford Appleton Laboratory.

The project received support from the Quantum Technologies for Fundamental Physics (QTFP) program, a joint STFC-EPSRC initiative.