IT'S A QUANTUM UNIVERSE

Researchers publish new guide to measuring spacetime fluctuations

Signatures of Correlation of Spacetime Fluctuations in Laser Interferometers

University of Warwick

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Cardiff's Gravity Exploration Institute team working on QUEST experiment. Credit: H Grote, Cardiff University.

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Credit: H Grote, Cardiff University

A team of researchers led by the University of Warwick has developed the first unified framework for detecting “spacetime fluctuations” - tiny, random distortions in the fabric of spacetime that appear in many attempts to unite quantum physics and gravity.

These subtle fluctuations, first envisaged by physicist John Wheeler, are thought to arise naturally in several leading theories of quantum gravity. But because different models of gravity predict different forms of these fluctuations, experimental teams have until now lacked clear guidance on what to look for.

The new study, published in Nature Communications addresses this challenge by sorting spacetime fluctuations into three broad categories, each defined by how organised the fluctuations are in space and time. For each category, the researchers mapped out the distinct, measurable signatures that would appear in laser interferometers - from the 4km long LIGO, to compact laboratory systems such as QUEST and GQuEST being developed in the UK (Cardiff University) and USA (Caltech) respectively.

Dr. Sharmila Balamurugan, Assistant Professor, University of Warwick and first author said: “Different models of gravity predict very different underlying trends in the random spacetime fluctuations, and that has left experimentalists without a clear target. Our work provides the first unified guide that translates these abstract, theoretical predictions into concrete, measurable signals.

“It means we can now test a whole class of quantum-gravity predictions using existing interferometers, rather than waiting for entirely new technologies. This is an important step towards bringing some of the most fundamental questions in physics firmly into the realm of experiment.”

The study found that:

• Tabletop interferometers beat LIGO in bandwidth
   Despite being far smaller than LIGO, QUEST and GQuEST could provide more detailed information about the nature of spacetime fluctuations. Their wide frequency coverage allows them to detect all the characteristic signatures.
• LIGO is an excellent “yes/no” detector.
   Thanks to its long arm cavities, LIGO is highly sensitive to the mere presence of spacetime fluctuations — although the relevant frequencies lie above the range currently available in public data.
• A long-running debate is resolved.
   A debate about whether arm cavities help or hinder detection has been answered as here arm cavities do enhance an interferometer’s sensitivity to spacetime fluctuations, depending on the type of fluctuation being tested.

Dr. Sander Vermeulen, Caltech, co-author of the study said: “Interferometers can measure spacetime with extraordinary precision. However, to measure spacetime fluctuations with an interferometer, we need to know where - i.e. at what frequency - to look, and what the signal will look like. With our framework we can now predict this for a wide range of theories. Our results show that interferometers are powerful and versatile tools in the quest for quantum gravity.”

Crucially, the new framework developed here is agnostic of the underlying mechanism for the fluctuations: it requires only the mathematical description of the hypothesised fluctuations and the geometry of the instrument. This makes it a powerful tool not only for quantum-gravity tests but also for searches for stochastic gravitational waves, dark-matter signatures, and certain forms of instrumental noise.

Prof Animesh Datta, Professor of Theoretical Physics at Warwick concluded: “With this methodology, we can now treat any proposed model of spacetime fluctuations in a consistent, comparable way. In the coming years, we can use this to design smarter tabletop interferometers to confirm or refute possible theories of quantum or semiclassical gravity and even test new ideas about dark matter and stochastic gravitational waves.”

ENDS

Notes to Editors

Image Credits: H Grote, Cardiff University.

About the paper and funding:

The paper ‘Signatures of Correlation of Spacetime Fluctuations in Laser Interferometers’ has been published in Nature Communications. DOI: https://doi.org/10.1038/s41467-025-67313-3

This work was funded by the UK STFC “Quantum Technologies for Fundamental Physics” program (Grant Numbers ST/T006404/1, ST/W006308/1 and ST/Y004493/1) and the Leverhulme Trust under research grant ECF-2024-124 and RPG-2019-022.

 About the University of Warwick

Founded in 1965, the University of Warwick is a world-leading institution known for its commitment to era-defining innovation across research and education. A connected ecosystem of staff, students and alumni, the University fosters transformative learning, interdisciplinary collaboration, and bold industry partnerships across state-of-the-art facilities in the UK and global satellite hubs. Here, spirited thinkers push boundaries, experiment, and challenge conventions to create a better world.

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Journal

Nature Communications

DOI

10.1038/s41467-025-67313-3 

Method of Research

Computational simulation/modeling

Article Title

Signatures of correlation of spacetime fluctuations in laser interferometers

Quantum measurements with entangled atomic clouds

University of Basel

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With three atomic clouds whose spins (blue) are entangled with each other at a distance, the researchers can measure the spatial variation of an electromagnetic field.

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Credit: Illustration: Enrique Sahagún, Scixel / University of Basel, Department of Physics

Researchers at the University of Basel and the Laboratoire Kastler Brossel have demonstrated how quantum mechanical entanglement can be used to measure several physical parameters simultaneously with greater precision.

Entanglement is probably the most puzzling phenomenon observed in quantum systems. It causes measurements on two quantum objects, even if they are at different locations, to exhibit statistical correlations that should not exist according to classical physics – it’s almost as if a measurement on one object influences the other one at a distance. The experimental demonstration of this effect, also known as the Einstein-Podolsky-Rosen paradox, was awarded the 2022 Nobel Prize in physics.

Now, a research team led by Prof. Dr. Philipp Treutlein at the University of Basel and Prof. Dr. Alice Sinatra at the Laboratoire Kastler Brossel (LKB) in Paris has shown that the entanglement of spatially separated quantum objects can also be used to measure several physical parameters simultaneously with increased precision. The researchers recently published their results in the scientific journal Science.

Improved measurements through entanglement

“Quantum metrology, which exploits quantum effects to improve measurements of physical quantities, is by now an established field of research,” says Treutlein. Fifteen years ago, he and his collaborators were among the first to perform experiments in which the spins of extremely cold atoms were entangled with each other. The entanglement allowed them to measure the direction of the atomic spins (which can be imagined as tiny compass needles) more precisely than would have been possible with independent spins without entanglement.

“However, those atoms were all in the same location,” Treutlein explains: “We have now extended this concept by distributing the atoms into up to three spatially separated clouds. As a result, the effects of entanglement act at a distance, just as in the EPR paradox.”

The idea behind this is that if one wants to measure, for instance, the spatial distribution of an electromagnetic field, one could use an entangled state of spatially separated atomic spins. Similarly to the measurement at a single location, the entanglement could then reduce the measurement uncertainties due to quantum mechanics and, to a large degree, also cancel other disturbances that act equally on all the atomic spins.

“So far, no one has performed such a quantum measurement with spatially separated entangled atomic clouds, and the theoretical framework for such measurements was also still unclear,” says Yifan Li, who was involved in the experiment as a postdoc in Treutlein’s group. Together with their colleagues at the LKB, Treutlein and his team investigated how the measurement uncertainty for the spatial distribution of an electromagnetic field could be minimized using such entangled clouds.

To achieve this, they first entangled the atomic spins into a single cloud and then split the cloud into three entangled parts. With only a few measurements, they were able to determine the field distribution with a distinctly better precision than would have been expected without the spatial entanglement.

Applications in atomic clocks and gravimeters

“Our measurement protocols can be directly applied to existing precision instruments such as optical lattice clocks,” says Lex Joosten, PhD student in the Basel group. In such clocks, atoms are trapped in an optical lattice created by laser beams and then used as extremely precise “clockworks”. The methods of the Basel researchers could be used to reduce specific measurement errors arising from the distribution of atoms across the lattice, thereby improving the precision of time measurements.

Another example of a practical application is atom interferometers, which can be used to measure the Earth’s gravitational acceleration. For some applications of these instruments, known as gravimeters, the main quantity of interest is the spatial variation of gravity, which can be measured with higher precision than before using the entanglement approach.

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Journal

Science

DOI

10.1126/science.adt2442 

Method of Research

Experimental study

Article Title

Multiparameter estimation with an array of entangled atomic sensors

Article Publication Date

22-Jan-2026

Body-focused (FEMALE) teens more likely to experience anxiety and depression at 20

A cluster analysis of health behaviors and their relationship to weight stigma, neuroticism and psychological wellbeing

University of Warwick

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Teenage girls who maintain a ‘normal’ body weight through constant dieting and exercise may look ‘healthy’ but should be seen as a vulnerable group according to new research from the University of Warwick.

The study, led by Dr Dimitra Hartas, finds that 17-year-old women of normal weight who closely manage their bodies through strict regimes of diet and exercise – focused on “clean eating”, fitness, and constant self-monitoring rather than food deprivation – face heightened risks to their psychological health. Many reported experiences of weight stigma, high levels of anxiety-related traits, and thoughts of self-harm and suicide.

By the age of 20, these young women were more likely to experience symptoms associated with anxiety and depression, alongside psychological distress and poorer overall wellbeing.

The research challenges the widespread assumption that dieting and regular exercise are always markers of good health. Instead, it highlights how body management has become closely tied to identity, self-worth, and social acceptance – particularly for young women.

“In an image-saturated culture, young women are praised for being fit and slim,” said Dr Dimitra Hartas, Reader at the University of Warwick. “But beneath this veneer of health lies a troubling reality. For many, managing body weight is not about wellbeing – it is about meeting cultural expectations and earning a sense of worth.”

The study points to a broader societal shift in which personhood has become a project of constant self-optimisation, where the ‘ideal body’ is narrowly defined and weight is treated as a measure of personal worth.

In social media culture, body satisfaction has become a form of currency, with ‘slim’ increasingly seen as synonymous with ‘worthy’. As a result, young women often work hard to look like the best version of themselves, rather than to feel or be well.

“This pressure for the female body to shrink is a form of social control,” Dr Hartas said. “It restricts women’s physical and symbolic space, shaping how they see themselves and how society permits them to exist. The mental health cost of this pressure is significant and too often overlooked.”

The findings sit within a wider and worrying context. Recent studies show that one in three women aged 16–24 report experiencing mental ill health, with rates of self-harm among young women having quadrupled since 2000.

Dr Hartas argues that recognising young women of normal weight who engage in constant dieting and exercise as a vulnerable group is essential for improving mental health prevention, education, and support.

“Health messaging needs to move beyond weight and appearance,” she said. “We need to ask not just how young women look, but how they are actually doing – psychologically, emotionally, and socially.”

“These findings show that schools and colleges need to do much more to support young people’s health,” said Dr Michael C Watson from the Institute of Health Promotion and Education (IHPE). “We need to move beyond BMI and weight management towards promoting exercise, sleep and healthy eating, while also tackling body image and fat shaming. This is a complex challenge that won’t be solved by one-off or isolated interventions.”

ENDS

About the University of Warwick 

Founded in 1965, the University of Warwick is a world-leading institution known for its commitment to era-defining innovation across research and education. A connected ecosystem of staff, students and alumni, the University fosters transformative learning, interdisciplinary collaboration and bold industry partnerships across state-of-the-art facilities in the UK and global satellite hubs. Here, spirited thinkers push boundaries, experiment and challenge convention to create a better world.

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Journal

Current Psychology

DOI

10.1007/s12144-025-08652-8 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

A cluster analysis of health behaviours and their relationship to weight stigma, neuroticism and psychological wellbeing in adolescents and young adults: a population-based study

Article Publication Date

16-Jan-2026

 

A new method to unlock vast lithium stores

Researchers at Columbia Engineering have developed a faster, cheaper, and more environmentally friendly way to extract this critical mineral

Columbia University School of Engineering and Applied Science

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Demand for lithium is skyrocketing as factories across the world churn out electric vehicles and the massive batteries that make wind turbines and solar panels reliable sources of energy. Unfortunately, current methods for producing lithium are slow and require high-quality feedstocks that are found in relatively few locations on the planet. Ironically, the environmental costs are also significant: refining the mineral behind clean energy requires large amounts of land and pollutes water supplies that local communities depend on.

In a new paper, researchers from Columbia Engineering describe a new method for extracting lithium that could dramatically shorten processing time, unlock reserves that existing methods can’t tap, and reduce environmental impact. Their technique uses a temperature-sensitive solvent to extract lithium directly from the brines found in deposits across the world. Unlike the current technologies, this approach can efficiently extract lithium even when the mineral is found in very low concentrations and contaminated with similar materials.

The results, detailed in a paper published today in Joule, show that the innovation, called switchable solvent selective extraction, S3E (pronounced S three E), can extract lithium with strong selectivity: up to 10 times higher than for sodium, and 12 times higher than for potassium. The process also excludes magnesium, a common contaminant in lithium brines, by triggering a chemical precipitation step that separates it out.

Improving on Solar Evaporation

Roughly 40% of lithium production begins with a salty brine that’s found in large reservoirs that form under deserts. Nearly all of that lithium is extracted using a technique called solar evaporation, where the brine is pumped into sprawling ponds that bake under the desert sun — for up to two years — until enough water evaporates. This is only feasible in dry, flat regions with vast amounts of land, such as Chile’s Atacama Desert or parts of Nevada. It also consumes large volumes of water in places that can scarcely afford it.

“There’s no way solar evaporation alone can match future demand,” said Ngai Yin Yip, La Von Duddleson Krumb Associate Professor of Earth and Environmental Engineering at Columbia University. “And there are promising lithium-rich brines, like those in California’s Salton Sea, where this method simply can’t be used at all.”

Unlike conventional lithium recovery methods, S3E doesn't rely on binding chemicals or extensive postprocessing. Instead, the process exploits the way lithium ions interact with water molecules in a solvent system that changes its behavior based on temperature. At room temperature, the solvent pulls lithium and water from the brine. When heated, it releases the lithium, along with water, into a purified stream and regenerates itself for reuse.

An Approach with Tremendous Potential

In lab tests using synthetic brines modeled on the Salton Sea, a geothermal region in Southern California estimated to hold enough lithium to supply more than 375 million EV batteries, the system recovered nearly 40% of the lithium over just four cycles with the same solvent batch. That suggests a viable path toward continuous operation.

“This is a new way to do direct lithium extraction,” said Yip. “It’s fast, selective, and easy to scale. And it can be powered by low-grade heat from waste sources or solar collectors.”

The team emphasized that this is a proof-of-concept study. The system hasn’t yet been optimized for yield or efficiency. But even in this early form, S3E appears promising enough to offer an alternative to evaporation ponds and hard-rock mining, the two approaches that dominate the lithium supply chain today and come with steep tradeoffs.

As the global clean energy transition picks up speed, technologies like S3E could play a crucial role in keeping it on track—by making it possible to extract lithium faster, more cleanly, and from more places than ever before.

“We talk about green energy all the time,” said Yip. “But we rarely talk about how dirty some of the supply chains are. If we want a truly sustainable transition, we need cleaner ways to get the materials it depends on. This is one step in that direction.”

Interested parties seeking collaboration, licensing, or application of the technology may express their interest here.

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Journal

Joule

Article Title

A New Method to Unlock Vast Lithium Stores

Article Publication Date

21-Jan-2026

 

Lithium study yields insights in the fight against HIV

Study in human cells finds low-cost drug keeps virus dormant through an unexpected pathway, pointing the way to new treatments

McGill University

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Lithium, a widely used treatment for bipolar disorder and other mood disorders, has shown early promise in suppressing HIV, McGill University researchers report.

A new study published in iScience found lithium can prevent infected cells from reactivating, and that it does so through an unexpected biological mechanism.

The findings point toward future treatments designed to mimic lithium’s beneficial effects while avoiding its broader impacts on the body.

“One major thrust in HIV cure research is asking whether existing drugs can be repurposed. Because lithium is inexpensive and already approved for other uses, it offers a faster starting point than developing a new drug from scratch,” said senior author Andrew Mouland, Professor in McGill’s Department of Medicine and Head of the HIV-1 RNA Trafficking Laboratory at the Lady Davis Institute for Medical Research.

The results do not mean people with HIV should take lithium, he said. The psychoactive drug can cause significant side effects and has not yet been tested in humans as an HIV treatment.

A step toward a ‘functional cure’

An estimated 40.8 million people around the world were living with HIV in 2024. Even with effective antiretroviral therapy, the virus can remain hidden in immune cells and rebound if daily treatment stops.

A “functional cure” aims to overcome this challenge. Rather than eliminating the virus entirely, the goal is to keep HIV dormant, so it cannot restart infection, potentially reducing the need for continuous daily medication.

“In our experiments, lithium directly suppressed HIV reactivation in lab-grown human cells, something that had not been clearly demonstrated before,” said first author Ana-Luiza Abdalla, who conducted the work as a PhD student at McGill and is now a postdoctoral fellow at the Montreal Neurological Institute.

As well, the team gained new insights into the mechanism involved.

Earlier research suggested lithium might work by activating autophagy, the cell’s recycling system. Because many drugs studied in HIV cure research affect this pathway, scientists assumed autophagy was responsible for keeping the virus dormant.

This study challenges that assumption, made possible by a fluorescence-based test developed by University of Manitoba researcher Thomas Murooka that allows scientists to distinguish between dormant and active virus in cells.

“What surprised us was that the effect persisted even when we disrupted autophagy,” Abdalla said. “That suggests other pathways are involved, possibly ones HIV relies on to restart.”

About the study

“Lithium attenuates HIV-1 latency reversal in an autophagy-independent way” by Ana-Luiza Abdalla, Gabriel Guajardo-Contreras, Meijuan Niu, Thomas Murooka and Andrew J. Mouland was published in iScience. Funding was provided by the Canadian Institutes of Health Research.

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Journal

iScience

DOI

10.1016/j.isci.2025.114085 

Method of Research

Experimental study

Article Title

Lithium attenuates HIV-1 latency reversal in an autophagy-independent way