Physicists Create a Supersolid at Room Temperature — a State of Matter That Is Solid and Liquid at Once

Physicists have created one of the strangest states of matter known to science without the deep freeze it has always required. An international team led by the University of Warsaw has observed a supersolid — a state that flows like a liquid with no friction while holding the regular, repeating pattern of a crystal — at room temperature, inside a tiny light-trapping device that can be tuned with an ordinary electric voltage. The results were published in the journal Science Advances, according to the University of Warsaw.

The finding matters because, until now, supersolids have lived almost exclusively in the coldest places on Earth. Every previous observation required atoms cooled to a few billionths of a degree above absolute zero, in machines that fill a laboratory and cost a fortune to run. The new experiment replaces the ultracold atoms with hybrid particles made of light and matter, and it works on a benchtop, at room temperature — and, according to the researchers, in cavities that can operate at temperatures approaching 60 degrees Celsius.

“Our liquid-crystal microcavities can operate even at temperatures approaching 60°C,” said Professor Wiktor Piecek of the Military University of Technology in Poland, whose group developed the liquid-crystal structures used in the experiment, according to the University of Warsaw.

The work was carried out by researchers from the Faculty of Physics at the University of Warsaw, the Military University of Technology, IBM Research Zurich and the French National Centre for Scientific Research (CNRS), working together in a consortium known as TopoLight. The paper’s first author is Dr Marcin Muszyński, now a postdoctoral researcher at The City College of New York. The study was published in Science Advances under the title “Observation of a supersolid phase in a spin-orbit coupled exciton-polariton Bose-Einstein condensate”.

A supersolid sounds like a contradiction, and in everyday experience it is one. A crystal is rigid and ordered; a liquid flows. Yet quantum mechanics allows a state that does both at once. As the University of Warsaw explained in its announcement, a superfluid is a liquid in which viscosity disappears entirely — it can flow through the narrowest channels without resistance, and an oar dipped into it would feel almost no drag until a critical speed is reached. A supersolid keeps that frictionless flow while also arranging itself into a regular, crystal-like pattern. It is, in the words of the researchers, a liquid that has decided to be a crystal at the same time.

The idea is more than half a century old. As early as the 1960s, physicists predicted that a superfluid could develop a periodic crystal-like structure. Soviet physicists Alexander Andreev and Ilya Lifshitz argued in 1969 that the helium-4 isotope could straddle the solid and liquid states, and the Nobel laureate Anthony Leggett formalised the idea in 1970. For decades it remained a theoretical prediction. In 2004, a team at Pennsylvania State University reported evidence of supersolidity in solid helium cooled to less than a tenth of a degree above absolute zero, but later work by other physicists, including John Reppy at Cornell University, suggested the signal came from surface effects in the helium rather than from a true supersolid, and the claim faded.

Definitive proof arrived only in 2017, when two groups working independently — one at ETH Zurich led by Tilman Esslinger and Tobias Donner, the other at the Massachusetts Institute of Technology led by Wolfgang Ketterle — created supersolid-like states in Bose-Einstein condensates of ultracold atoms. The ETH team placed a small amount of rubidium gas in a vacuum chamber, cooled it to a few billionths of a kelvin above absolute zero, and coupled it to two optical resonators until the atoms spontaneously crystallised while keeping their superfluidity. Both results were published in Nature in March 2017. Two years later, in 2019, three further groups — in Stuttgart, Innsbruck and Pisa — observed supersolid behaviour in dipolar condensates made of highly magnetic dysprosium atoms. Every one of those experiments needed temperatures within a whisper of absolute zero.

The Warsaw-led team took a completely different route. Instead of cooling atoms, it worked with light. The researchers studied exciton polaritons, hybrid quasiparticles formed when light is trapped inside an optical microcavity and couples strongly to matter. Although each polariton exists for only a few picoseconds — a few trillionths of a second — that is long enough for them to form a Bose-Einstein condensate, the quantum state in which many particles behave as a single entity, and to flow as a quantum superfluid. The concept of a polariton condensate itself dates to 2006, when Jacek Kasprzak and colleagues reported Bose-Einstein condensation of exciton polaritons in a cadmium telluride microcavity at 19 kelvin in the journal Nature.

The new device is a sandwich built at the scale of light itself. The optical microcavity was filled with a specially designed liquid crystal and coated with an organic semiconductor called MeLPPP, short for methyl-substituted ladder-type poly(paraphenylene). The combination allowed strong coupling between light and matter at room temperature. Laser pulses supplied the energy that drove the quantum behaviour, and the light escaping from the cavity carried the evidence.

How do you recognise a supersolid?

The tell-tale sign was a pattern in the light. When the condensate entered the supersolid phase, regularly spaced bright fringes appeared in the light emitted from the sample, showing that the condensate had spontaneously formed a periodic density modulation — the hallmark of crystallisation. That alone would have been striking. But the experiment revealed something more remarkable still.

With every laser pulse that excited the sample, the fringes appeared at a different position. Each time, the quantum system independently chose one of many equivalent configurations, with no outside influence deciding where the pattern would land. That behaviour is the fingerprint of what physicists call spontaneous symmetry breaking: the system starts out symmetric, with no preferred arrangement, and then breaks that symmetry by picking one arrangement at random. Theory had predicted that a supersolid would behave exactly this way.

“This is a textbook example of spontaneous symmetry breaking,” said Professor Guillaume Malpuech of Institut Pascal at CNRS, according to the University of Warsaw. “Theory predicted that the supersolid could choose among several equivalent states, and that is exactly what we observed.”

At the same time, the condensate displayed a second, independent form of order. It exhibited a persistent spin helix — a periodic modulation in the polarisation of the emitted light. The researchers therefore observed two distinct kinds of order simultaneously: one in the polarisation of the light and another in its intensity. The double signature strengthened the case that what they were seeing was genuinely a supersolid, and not an artefact of the cavity. As ScienceAlert reported, the stripes lined up in slightly different places with every refresh of the condensate, which showed that the pattern came from the quantum state itself rather than from anything imposed by the microcavity.

The experiment also exploited a feature that ultracold-atom systems cannot offer: the cavity can be controlled with voltage. Because the microcavity contains a liquid crystal, whose molecules rotate under an applied electric field, the optical properties of the device can be adjusted dynamically. According to the University of Warsaw, liquid-crystal microcavities provide the first electrically tunable platform for investigating supersolid exciton-polariton condensates — a laboratory in which the quantum state can be steered from outside, rather than rebuilt from scratch for every new question.

A race against time in the laboratory

Getting the result was, by the researchers’ own account, far harder than expected. The organic semiconductor gradually reacted with the liquid crystal, so every measurement had to be completed within only a few hours of the sample being assembled. Planning was everything.

“We had to plan the entire sequence of experiments in advance,” said Dr Muszyński, according to the University of Warsaw. “Repeating a measurement meant fabricating an entirely new sample.”

The most important measurements were carried out at IBM Research Zurich, where thin films of the organic semiconductor were deposited onto photonic structures fabricated at the Military University of Technology. The IBM team had studied the MeLPPP semiconductor for many years and had previously observed Bose-Einstein condensation in the material. “This was the first time we combined it with a liquid-crystal microcavity,” said Thilo Stöferle of IBM Research, according to the university. Multiple samples were tested, the team reported, and the results were reproduced each time and backed up by computer simulations.

The work sits inside a wider European research effort. The team worked as part of the TopoLight consortium, a project funded by the European Union’s Horizon 2020 programme under grant agreement 964770, which set out to build a soft-matter platform for optical devices using liquid crystals and polaritons. Its stated aim was to demonstrate tunable topological emitters based on room-temperature Bose-Einstein condensates, and to create states of light that flow in one direction and resist scattering. The supersolid result is the most striking product of that programme so far.

It is also not the only room-temperature supersolid reported this year. In May 2026, a separate team reported in the journal Nature Nanotechnology that it had achieved a room-temperature supersolid by integrating single-crystal halide perovskites with a patterned nanograting, driving the system with optical parametric oscillation into a striped, self-organised state. The two results use different materials and different mechanisms, but they point in the same direction: the deep freeze is no longer the price of admission to supersolid physics. A third line of work, described in a preprint, reports room-temperature polariton supersolids in perovskite photonic-crystal devices. The field, in short, has become a small race — and the Warsaw-led result is the first to add electrical tunability to the achievement.

The caveats the team itself states

The result is a genuine advance, but it is not a finished technology, and the researchers and the coverage of their work are careful about the limits. The superfluid side of the claim still needs further quantitative testing, as the paper itself acknowledges — the evidence for frictionless flow rests on the appearance of quantum vortices, flaws in the stripe patterns that indicate superfluid behaviour, and those vortices have yet to be interrogated in full detail. The materials also degrade: the optical quality of the samples fell away over periods ranging from days to weeks, probably because of the interaction between the liquid crystal and the semiconductor, and each particle in the condensate lasts only a fraction of a second. No practical device has been demonstrated, and none was claimed. What has been demonstrated is a platform — a way of studying the physics — and the platform is, for now, a laboratory instrument rather than a product.

That honesty matters, because the history of supersolids includes a cautionary tale. The 2004 helium claim was celebrated, then quietly undermined as other laboratories showed the effect could be explained without any new state of matter. The 2017 atomic-gas results survived because they were reproduced by independent groups using different methods, and because the evidence was examined sceptically before it was accepted. The Warsaw result has been peer-reviewed and published in Science Advances, it has been reproduced across multiple samples, and its central observation — the fringes that move with every pulse — is precisely the behaviour theory predicted. But the strongest validation will come the same way it did in 2017: when other laboratories build their own liquid-crystal cavities and see the same stripes shift with every pulse.

Analysis: Why It Matters

The headline fact — a supersolid at room temperature — is easy to state and easy to understate. What it actually changes is the economics of an entire branch of physics. For sixty years, the study of supersolids has been hostage to the coldest technology humans can build. A dilution refrigerator, the machine that cools atoms to billionths of a degree above absolute zero, costs hundreds of thousands of dollars, needs a dedicated room, a trained team and a constant supply of helium, and it produces a handful of experiments a day. A liquid-crystal microcavity that works at room temperature costs a tiny fraction of that, fits on a bench, and can be driven by a laser and a voltage supply. If the platform proves robust, the number of laboratories that can study supersolid physics will grow from a few dozen in the world to potentially hundreds. That is not a marginal improvement; it is the difference between a priesthood and a field.

The deep-freeze barrier has defined quantum physics for a century

Almost every exotic quantum state that physicists care about — superconductivity, superfluidity, Bose-Einstein condensation — was first found in the cold, and for a simple physical reason: heat is noise, and quantum order is fragile. Thermal vibrations scramble the delicate correlations that make a quantum state what it is. The history of condensed-matter physics can be read as a long campaign to push quantum behaviour to higher temperatures, because every degree gained makes the phenomenon cheaper to study and closer to useful. Superconductors that work at liquid-nitrogen temperature transformed power engineering; polariton condensates that work at room temperature, first shown in organic materials in the 2010s, opened the door to lasers and optical switches that do not need a cryostat. The supersolid is simply the latest, and perhaps the most symbolically loaded, member of that list. It was the state that most obviously belonged to the deep freeze — a crystal that flows — and it has now been taken out of it. The psychological effect on the field may matter as much as the technical one: if a supersolid works at room temperature, researchers will ask, with new confidence, what else does.

A quantum laboratory you can tune with a dial

The second reason this result stands out is not the temperature but the control. Ultracold-atom supersolids are magnificent instruments, but they are also rigid: changing the experiment usually means rebuilding the apparatus, realigning lasers, and re-cooling the atoms. The Warsaw device is different in kind. Because the cavity is filled with a liquid crystal, an applied voltage rotates the crystal’s molecules, changes the refractive index of the cavity, and steers the polaritons’ behaviour from outside. The researchers describe it as the first electrically tunable platform for this physics, and the claim deserves emphasis. A tunable platform is a laboratory that can ask many questions in sequence rather than one question per build. It is the difference between a telescope fixed on one star and a telescope that can be pointed. For the study of spin-orbit coupling — the linking of light’s polarisation to its motion that produced this supersolid — that flexibility is the point. The same device that made a supersolid can, in principle, be retuned to explore neighbouring quantum phases, topological states of light, and the vortices that the team has not yet fully characterised. The TopoLight programme’s original goal was precisely this: topological emitters and states of light that can be switched electrically. The supersolid is a demonstration that the platform can reach genuinely new physics, not only incremental engineering.

Light-based computing has been waiting for exactly this

The applications the team names — ultrafast photonic devices, neuromorphic computing accelerators, and highly sensitive optical sensors — are not afterthoughts. They are the reason funding agencies paid for the work. Modern computing is running into the limits of electronics: transistors are approaching atomic scales, chips generate heat faster than it can be removed, and the energy cost of training large artificial-intelligence models has become a public concern. Light offers a way out, because photons do not generate the same resistive heat and can carry many signals at once. The obstacle has always been control: light is hard to slow down, hard to store, and hard to make interact with itself. Polaritons solve part of that problem, because they are part matter and part light — they interact like matter and travel like light. A supersolid of polaritons adds a new tool: a quantum fluid of light that is both coherent and patterned, and whose pattern can be moved with a voltage. That is, in principle, a switch, a memory element and a sensor in one structure. None of that exists yet as a device. The samples degrade within days, the particles live for picoseconds, and the superfluid flow has yet to be measured quantitatively. But the history of polaritonics suggests the gap between a laboratory demonstration and a prototype can close quickly once the physics is understood — the first polariton laser followed the first polariton condensate by only a few years, and room-temperature polariton lasers are now a routine research tool. The honest reading is that the Warsaw result is a beginning, not a product launch, and beginnings are what matter most in this field.

The credibility test is the same one that caught helium in 2004

There is a reason to be both excited and careful. Supersolidity has produced one famous false alarm already, and the field remembers it. The 2004 helium result was published in good faith, examined by the best laboratories in the world, and eventually explained away as a surface effect. The 2017 atomic-gas results survived because they were reproduced independently, in different laboratories, by different methods, and because the evidence was interrogated rather than celebrated. The Warsaw result has cleared peer review at Science Advances, it was reproduced across multiple samples, and its key evidence — the fringes that land in a different place with every laser pulse — is exactly what theory predicted for spontaneous symmetry breaking. But one laboratory, however careful, is not a consensus. The paper itself leaves the superfluid behaviour partly unquantified, and the Brighter Side’s coverage of the work notes that the superfluid aspect needs further quantitative testing. The right stance is the one the physics community will take: enthusiastic, and waiting for the second laboratory. That is not scepticism for its own sake; it is how the field earned its credibility after 2004. The perovskite supersolid published in Nature Nanotechnology in May 2026 is, in this light, an encouraging sign — two different material platforms reaching the same physics in the same year makes a shared artefact less likely, though the two experiments are different enough that neither validates the other directly.

A European science story with a long tail

There is also a quieter story here, about where the work was done and who paid for it. The research was led by a Polish university, built on photonic structures fabricated at a Polish military university, measured at IBM’s Zurich laboratory, and interpreted with French theorists — and funded in part by the European Union’s Horizon 2020 programme. A decade ago, the centre of gravity for this kind of physics was firmly in the United States and Switzerland. The TopoLight consortium shows a different geography: a European network in which a Warsaw laboratory can lead a result that the whole world covers. For the European Union, which has spent years trying to convert research funding into technological sovereignty in semiconductors and quantum technology, a room-temperature quantum platform built from liquid crystals — a technology Europe already manufactures at scale for displays — is an unusually convenient story. Whether it becomes an industry is a question for the next decade, and the honest answer today is that nobody knows. But the conditions are unusually favourable: the materials are cheap, the fabrication is compatible with existing photonics, and the device works in the open air. Those are the ingredients from which, historically, real technologies have grown.

What to Watch Next

1. Independent reproduction: the decisive test is whether other laboratories — in the United States, Asia or elsewhere in Europe — build liquid-crystal polariton cavities and see the same shifting fringes. Watch for a second group’s confirmation in the coming months.
2. Quantifying the superfluid flow: the team has flagged the quantum vortices in the stripe pattern as the next target. A direct measurement of frictionless flow — for example, showing that the condensate moves around an obstacle without resistance — would complete the proof.
3. Longer-lived samples: the organic semiconductor reacts with the liquid crystal and degrades the device within days. Watch for a more stable material combination, which would turn a laboratory demonstration into a durable platform.
4. The perovskite comparison: the May 2026 perovskite-nanograting supersolid and the new liquid-crystal result are two different routes to the same physics. Watch whether the two communities converge on a shared set of tests for what counts as a room-temperature supersolid.
5. First devices: the team’s stated applications are ultrafast photonic devices, neuromorphic computing and polarisation-sensitive sensors. The first prototype — even a simple voltage-controlled optical switch based on the supersolid — would be the moment this leaves pure physics.
6. The TopoLight programme’s next results: the consortium’s original goal was electrically tunable topological states of light. Watch for follow-up papers using the same liquid-crystal platform to demonstrate topological lasers or protected light flow at room temperature.

Sources

• Phys.org — “Light-matter hybrids form supersolid quantum state at room temperature” (3 November 2026)
• University of Warsaw — “A new quantum state of matter”
• ScienceAlert — “Finally! Physicists Create an Exotic Quantum State of Matter That Works at Room Temperature” (8 November 2026)
• Muszyński et al., “Observation of a supersolid phase in a spin-orbit coupled exciton-polariton Bose-Einstein condensate”, Science Advances 12, eaee4875 (2026)
• Interesting Engineering — “European scientists spot new quantum state of matter at room temperature” (6 November 2026)
• Meng et al., “Hybrid perovskite-nanograting photonic architecture enables supersolidity at room temperature”, Nature Nanotechnology 21, 663–671 (2026)