A universal quantum state, long the subject of theoretical predictions, has been achieved for the first time in simulated quantum matter, according to researchers.

As materials reach tipping points, like the boiling of water or the loss of magnetic attraction, they begin to act universally. For the first time, scientists now say they have observed such an effect at the quantum level.

An international team of researchers from Caltech, the Université Paris-Saclay, and the Technical University of Munich revealed their quantum breakthrough in a recent paper published in the journal Nature. The work experimentally explores decades-old theories for the first time, providing new insight into quantum behaviors.

Universal Behavior

Tipping points are the liminal spaces of physics. In them, behavior can become universal, following the same rules, until differentiation occurs as a new state is entered. It could be compared to the orderly behavior usually seen in hotel hallways, while anything can happen behind closed doors.

To explore this concept, physicists use a theoretical framework known as conformal field theory.

“Physicists call this trait universality—the messy, microscopic details wash out, and only a few essential features survive,” explained co-author Jason Alicea, a Professor of Theoretical Physics at Caltech.

Simulating the Quantum World

Using simplified quantum computers called quantum simulators, the researchers tested two varieties of conformal field theories, Ising and tricritical Ising, both named for physicist Ernst Ising. The theories attempt to describe the emerging universal behavior of a quantum system at a tipping point into an exotic state like superposition or entanglement.

In conventional physics, these tipping points are driven by heat, but in this new work, the team is investigating exotic quantum effects that occur in the same temperature range, close to absolute zero. Like climbing the rungs of a ladder, laser manipulation can push the material through different quantum states once it reaches the tipping point.

Conformal field theory has allowed physicists to theoretically calculate the distance between these rungs for decades, but this is the first time they have been experimentally observed. 

In these quantum simulators, specialized lasers called optical tweezers trap arrays of neutral atoms. This experiment focused on strontium atoms, which the optical tweezers first trapped before other lasers excited them into high-energy Rydberg states. In this high-energy state, the atoms interact so strongly that they behave as a single entity. Finally, lasers were then also used to push the strontium atoms to the tipping point.

Viewing Quantum States

Many-body modulation spectroscopy is a new technique that researchers developed to measure the energy ladder. The technique uses lasers set to varying frequencies to shake the chain of strontium atoms and then measure the response. When a certain frequency caused a spike in the response measurement, the team identified a rung in the ladder. Notably, various settings produced results consistent with tricritical Ising theory.

“Even though we believed these theories to be true, it’s important to have an experimental realization, something you can poke and prod,” Alicea says. “To see those predictions borne out is a beautiful thing.”

Next, the researchers hope to scale up their work to study the effect on atoms in a two-dimensional grid, instead of in a single-file line. These theories are far less well understood in two dimensions, which intrigues the team.

“What excites me is that the technique doesn’t require knowing the answer in advance. Here we could check our measurements against exact predictions,” co-author Manuel Endres of Caltech concluded. “The next step is to point this at systems where nobody knows the response of the system quantitatively—including regimes that classical computers can’t reach.”

The paper, “Observation of Conformal Field Theory Spectra in a Quantum Simulator,” appeared in Nature on August 19, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.

A climate shock that unfolded about 304 million years ago is offering scientists a dramatic warning about how quickly Earth’s climate system can amplify an initial temperature rise. During the Late Paleozoic Ice Age, a relatively modest increase in global temperatures appears to have triggered a much larger episode of warming, as methane released from thawing permafrost intensified the greenhouse effect. Researchers say the ancient event provides a powerful geological parallel for the climate changes occurring today.

The study, led by Le Yao of the Nanjing Institute of Geology and Paleontology with contributions from University of Cincinnati geosciences professor Thomas Algeo and international colleagues, examined a short-lived warming episode during Earth’s penultimate ice age. Their findings suggest that global sea surface temperatures eventually increased by more than 7 degrees Celsius, or approximately 12 degrees Fahrenheit. The rise was not necessarily caused by one enormous initial pulse of carbon. Instead, it may have developed through a chain reaction in which warming activated additional natural sources of greenhouse gases.

The Late Paleozoic Ice Age extended across a vast span of geological time, when large ice sheets covered parts of the supercontinent Gondwana. Although the planet was in an “icehouse” state, atmospheric carbon dioxide and methane still had the power to destabilize the climate. The newly analyzed warming event is particularly significant because it occurred under ice-age conditions rather than during an already warm greenhouse world. That makes it a valuable analog for the modern Earth, which still contains continent-scale ice masses in Greenland and Antarctica.

According to the researchers, the initial climate disturbance may have been linked to volcanic activity. Volcanic emissions can inject carbon dioxide and other gases into the atmosphere, where they absorb outgoing infrared radiation and prevent some heat from escaping into space. The warming may also have been assisted by changes in Earth’s orbit. Over long cycles, variations in orbital shape alter the distribution of sunlight across the planet, influencing the growth and retreat of ice sheets and changing the seasonal balance of solar energy.

At first, the additional carbon may have produced only a limited temperature increase. But once warming crossed a critical threshold, frozen ground in high-latitude regions began to thaw. Permafrost contains large quantities of organic carbon preserved in frozen soils. When that material becomes available to microbes, decomposition can release carbon dioxide and methane. Methane is especially powerful over shorter atmospheric timescales because, molecule for molecule, it absorbs considerably more infrared radiation than carbon dioxide, even though it remains in the atmosphere for less time.

This process can create a positive climate feedback. An initial warming causes permafrost to thaw, thawing releases greenhouse gases, and the additional gases produce further warming. That extra heat can accelerate more thawing, allowing the cycle to reinforce itself. The researchers describe the ancient event as a transient global warming episode in which a comparatively modest carbon release appears to have crossed a climatic tipping point and initiated much more extensive carbon emissions from natural reservoirs.

The geological timescale of the ancient warming is also central to the study’s relevance. Algeo said the temperature change unfolded over tens of thousands of years, with warming occurring at an average rate of roughly one-tenth of a degree Celsius per 1,000 years. Modern warming is progressing far more rapidly. Researchers have observed an increase of nearly 1 degree Celsius in global sea surface temperature over approximately the past century, a rate many times faster than the average change reconstructed for the ancient event.

The comparison does not mean that Earth is destined to repeat the precise conditions of 304 million years ago. Continents, ecosystems, atmospheric composition and ice-sheet geometry were all different in the Late Paleozoic. However, the physics of greenhouse warming and the existence of carbon feedbacks remain relevant. Ancient climate records reveal how a system that appears stable can respond nonlinearly when warming activates processes capable of releasing additional greenhouse gases.

The findings also place human history in a broader planetary context. All recorded human civilization has developed during the most recent ice age, despite the fact that the term can sound incompatible with today’s climate. In scientific usage, Earth remains in an ice age because substantial permanent ice sheets still exist in Greenland and Antarctica. The ancient warming episode matters precisely because it demonstrates that an ice age does not guarantee a permanently cold or stable climate. Even within an icehouse world, a small disturbance can trigger rapid and substantial changes when reinforcing feedbacks are engaged.

The research, published in the Proceedings of the National Academy of Sciences, underscores why scientists closely monitor permafrost, polar ice and other climate-sensitive carbon stores. The ancient record cannot provide an exact forecast of future warming, but it shows that Earth’s climate has repeatedly responded to carbon disturbances with amplifying feedbacks. As modern emissions continue to raise temperatures at an exceptional rate, the geological evidence offers a clear message: the danger lies not only in the carbon released directly by human activity, but also in the natural carbon sources that warming can unlock.

Subject of Research: Ancient global warming, permafrost methane feedbacks, and climate tipping points during the Late Paleozoic Ice Age

Article Title: A transient global warming event during Earth’s penultimate icehouse

Web References: https://doi.org/10.1073/pnas.2601643123

References: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2601643123

Image Credits: Andrew Higley, University of Cincinnati

Keywords: climate change, global warming, ice age, Late Paleozoic Ice Age, permafrost, methane, climate feedback, tipping point, paleoclimate, geology, volcanic activity, Earth’s climate history