Researchers from a UK-led collaboration have successfully demonstrated a critical principle that could underpin the next generation of quantum sensors, marking an important milestone in the development of large-scale quantum detector systems.
The findings, published in the journal Nature, provide the first experimental evidence that a technique designed to eliminate disruptive background noise can operate effectively under realistic conditions.
The breakthrough is expected to support the future deployment of advanced atom interferometers capable of probing some of the Universe’s biggest mysteries.
The research forms part of the Atom Interferometer Observatory and Network (AION), a major UK initiative funded through the UK Research and Innovation (UKRI) Quantum Technologies for Fundamental Physics programme.
The project aims to build powerful new instruments capable of searching for dark matter and detecting previously inaccessible gravitational waves.
Solving a major challenge for quantum detector development
One of the biggest obstacles to large-scale quantum detectors is noise. Signals associated with phenomena such as dark matter or gravitational waves are incredibly weak and can be easily obscured by interference generated within the measurement system.
Atom interferometers, which are at the heart of the AION programme, rely on lasers to manipulate ultracold atoms into a quantum superposition state.
This allows atoms to effectively occupy two paths simultaneously before being recombined, enabling scientists to measure extremely small disturbances with exceptional precision.
However, the lasers used in these experiments introduce phase noise that is often far stronger than the signals researchers are attempting to detect.
To address this problem, scientists have proposed using two separate interferometers operating along the same baseline. By comparing their measurements, shared noise can be cancelled out, allowing genuine signals to emerge.
While this concept has long been viewed as essential for future quantum detector designs, it had never previously been demonstrated under conditions representative of real-world operation.
Tabletop experiment delivers clear results
The research team built a prototype system at the Imperial Ultracold Strontium Laboratory using two physically separated clouds of ultracold strontium-87 atoms controlled by a single ultra-stable laser.
To replicate the demanding conditions expected in future long-baseline instruments, the scientists deliberately introduced large amounts of additional noise into the experiment.
The result was dramatic. Individual interferometers became effectively unusable, with their signals completely overwhelmed. Yet when measurements from both devices were compared, researchers successfully recovered a clear signal and achieved performance limited only by the fundamental laws of quantum physics.
The team then added an artificial oscillating signal designed to mimic the effects of either a passing gravitational wave or a dark matter field. Despite the severe noise conditions, the signal remained clearly detectable using the differential measurement approach.
Building the UK’s first large-scale atom interferometer
The breakthrough supports plans for AION-10, a 10-metre atom interferometer that is expected to be installed within the Beecroft Building at the University of Oxford. Data collection is currently targeted before the end of the decade.
The Science and Technology Facilities Council (STFC) is playing a significant role in the project beyond funding oversight. Its Technology Department, together with RAL Space and particle physics specialists, is responsible for key engineering and scientific components of the instrument.
Among these contributions is the development of the detector’s main tower structure, which will support the central experimental apparatus and associated modules.
RAL Space’s Quantum Sensors team is also developing the ultracold strontium atom source required for the experiment. The process involves heating strontium to create a vapour before cooling the atoms with precision lasers and trapping them in an ultra-high vacuum environment.
Meanwhile, STFC particle physicists are modelling magnetic shielding systems designed to protect the atoms from external interference during measurements.
Opening a new window into the Universe
The successful demonstration provides the first direct validation of a core concept behind long-baseline quantum detector technology, helping to overcome one of the most significant technical hurdles facing the field.
AION is also linked to wider international efforts, including the MAGIS programme at Fermilab and proposed future projects at CERN. Together, these initiatives aim to extend atom interferometry techniques over much greater distances.
If successful, future quantum detector networks could explore gravitational wave frequencies beyond the reach of existing observatories while offering new opportunities to search for previously unknown forms of matter.
Scientists believe these technologies could ultimately reveal entirely new aspects of the Universe that remain hidden today.