Ultracold atoms recreate a decades-old prediction: matter appearing from empty space

Empty space may not be as empty as it looks. According to one of the strangest predictions in physics, a strong enough electric field can turn the energy of the vacuum itself into matter: a particle and its antimatter partner, appearing together out of nothing. Scientists have never been able to watch this happen directly, because the electric field needed is far stronger than anything a laboratory can produce. Now a team in China has found a way around the problem. Instead of trying to force the real effect to happen, they built a small, controllable copy of it using atoms cooled to almost the coldest temperature possible, held in place by laser light.

The work was reported on 31 October 2026. The researchers, based at the University of Science and Technology of China and working with colleagues at other institutions, trapped ultracold rubidium atoms in a single straight row of tiny laser traps. By arranging the atoms in a particular pattern, they created a laboratory version of what physicists call a “false vacuum”: a state that holds extra energy and can release it by producing pairs of particles. Then they watched, atom by atom, as the simulated pairs appeared.

At a glance

What happened: Researchers at the University of Science and Technology of China and other institutions used ultracold rubidium atoms trapped in a row of laser traps to simulate the Schwinger effect, the prediction that a strong electric field can create particle-antimatter pairs from the vacuum. The work was reported on 31 October 2026 and published in Physical Review Letters.

Why it matters: The real Schwinger effect has never been observed directly, because it needs an electric field far stronger than any laboratory can make. A controllable atomic model lets scientists test the theory, change the conditions, and watch the process unfold step by step.

What happens next: The team plans to study what happens when the simulated particles meet and collide, and to extend the experiment from a one-dimensional chain to two dimensions and to other theories, where new effects such as string breaking could appear.

What is the Schwinger effect?

To understand the experiment, it helps to start with the prediction it copies. Quantum electrodynamics is the theory that describes how light interacts with electrically charged particles such as electrons. According to this theory, a sufficiently strong electric field can, in principle, convert some of its energy into particles and their antimatter partners. A particle’s antimatter partner has the same mass as the particle but, for electrically charged particles, the opposite electric charge. The electron’s antimatter partner, for example, is the positron.

The creation of particle-antiparticle pairs from the vacuum by an electric field is known as the Schwinger effect, named after the physicist Julian Schwinger. In simple terms, the vacuum of empty space is not truly still. It holds energy, and under the right conditions that energy can turn into matter. The catch is the size of the field required. At the strengths of electric field that can be made in a laboratory, pair production is strongly suppressed, which means it happens so rarely that it is effectively impossible to see. That is why observing the effect experimentally has proved so challenging, and why, in its original form, it has never been observed directly.

The idea is closely connected to the idea of a “false vacuum”. A false vacuum is a state that looks stable but actually holds extra energy. Like a ball balanced on a hilltop, it can release that energy by changing into a lower-energy state, and in the case of the Schwinger effect, that release takes the form of particle-antiparticle pairs. Physicists care about this idea well beyond the laboratory, because similar processes may have played a part in the very early universe. But if the process cannot be seen in a real electric field, the theory is hard to test.

A laboratory copy made of cold atoms

The new experiment sidesteps the problem by building a model. The researchers used laser light to trap ultracold rubidium atoms in a one-dimensional chain, a straight row of tiny optical traps. An optical lattice is a pattern made by laser light that can hold atoms in place, a little like an egg tray holds eggs. In this case, every second trap on the chain contained two atoms, while the traps in between were empty.

That arrangement was the key to the whole experiment. “This arrangement is a ‘false vacuum,’ a state that can release energy by creating particle-antiparticle pairs,” explained Zhen-Sheng Yuan, co-senior author of the paper, in comments to Phys.org. The atoms in the traps played the part of the particles in the theory, and the way they were allowed to move between traps played the part of the electric field.

The team then changed the settings so that atoms could hop between neighbouring sites in a way that mimics pair creation, and tuned the background electric field to control the process. A quantum gas microscope, a specialised instrument that can photograph individual atoms, imaged the atoms at different times, letting the researchers watch the process happen. “We were inspired by the Schwinger effect, the prediction that a strong electric field can spontaneously create electron-positron pairs from the vacuum,” Yuan told Phys.org. “This is an example of ‘false vacuum decay,’ and in its original form it has never been observed directly. Our goal was to build a simple, controllable laboratory model with cold atoms, where we could simulate this process and tune how it unfolds.”

The study was led by first author Zi-Hang Zhu, and its authors include the Nobel laureate Frank Wilczek and Jian-Wei Pan, a leading figure in quantum science in China. The paper is titled “Probing False Vacuum Decay on a Cold-Atom Gauge-Theory Quantum Simulator” and appeared in Physical Review Letters in 2026. An earlier version of the work was shared on the arXiv preprint server in November 2024.

What the team found

The experiment worked as a working model of pair production, and the team could change the conditions and see how the outcome changed. They adjusted two things: the mass of the simulated particles in their system, and the strength of the background electric field. Both mattered. When the simulated particles were heavier, fewer pairs formed. When the electric field became too dominant compared with the other interactions in the model, fewer pairs formed as well. In other words, pair production was easiest in a middle range, not at the extremes, which matches what the theory expects.

The researchers also connected pair production to a quantity called the “vacuum persistence amplitude”. Its squared magnitude gives the probability that the initial vacuum survives unchanged. By tracking this, the team could measure how quickly the false vacuum decayed. They saw long-lived oscillations in this quantity in some settings, a wavelike rise and fall that persisted over time.

Another result came when the team set the simulated particle mass to zero. In that setting, they observed oscillations that resembled the collective excitations predicted by the Schwinger model, the coordinated wavelike movements that the theory says should appear. “Together, these show how cold atoms bring otherwise hard-to-observe quantum-field processes into a controlled laboratory,” Yuan said.

It is worth being clear about what was and was not shown. The experiment did not produce real electron-positron pairs, and it did not confirm the Schwinger effect in a real electric field. What it did was build a faithful analogue: a system whose mathematics matches the theory, in which the process can be started, tuned and watched. That is a different kind of result, but a useful one. It gives physicists a place to test ideas about a process they cannot yet see directly, and to check whether the theory behaves as expected when the conditions change.

Why a simulation is the right tool for this problem

Some readers may wonder why scientists would bother with a copy when the real thing is what matters. The answer is practical. The electric field needed to make the real Schwinger effect happen at a measurable rate is enormously strong, far beyond what any laboratory laser or magnet can produce today. A quantum simulator takes the opposite approach. Instead of recreating the exact physical conditions, it recreates the rules: the atoms and lasers are a stand-in, but the equations that describe them are the same equations that describe the real process. That lets researchers ask “what if” questions, changing the mass or the field and checking the answers against a working system rather than a calculation alone. A model is not a direct observation of the real effect, and the team describes its work as a platform for simulating and studying the process rather than a detection of it.

What comes next

The researchers are already planning the next steps. “We would now like to study what happens when these simulated particles meet, collide and scatter,” Yuan said. Collisions are where the physics gets richer: particles can bounce off each other, stick together, or turn into something else, and watching those events in a controlled model could reveal behaviour the theory has not yet pinned down.

The team also hopes to extend the experiment from a one-dimensional chain to two dimensions, and to other gauge theories, the family of theories that describe forces in nature. In those richer settings, new phenomena become accessible, including string breaking, a process in which the force holding two particles together snaps and creates new particles. That would take the simulator closer to the physics of quarks, the particles inside protons and neutrons, where similar effects are believed to happen but are extremely hard to study directly.

For now, the result is a new tool rather than a final answer. Physicists have a working laboratory model of one of the most elusive processes in quantum theory, and they can finally poke at it, change the settings, and watch what happens. If the model keeps behaving as the theory predicts, confidence in the theory grows. If it ever behaves differently, that would be even more interesting, because it would point to something the theory has missed.

Frequently asked questions

What is antimatter?

Antimatter is made of particles that mirror ordinary particles. Each antimatter particle has the same mass as its ordinary partner but the opposite electric charge. The positron is the antimatter partner of the electron. When a particle meets its antimatter partner, the two can annihilate each other, turning their mass into energy. Antimatter is rare in everyday life but is routinely made in small amounts in laboratories and hospitals, where positrons are used in PET scans.

What is a false vacuum?

A false vacuum is a state that looks stable but holds extra energy, like a ball resting in a shallow dip on a hillside. It can stay there for a long time, but it can also release its stored energy by dropping into a lower-energy state. In the Schwinger effect, that release produces particle-antiparticle pairs. Physicists also use the idea to think about the early universe, where a false vacuum may have driven a period of rapid expansion.

Did scientists really create matter from nothing?

Not in the everyday sense. No real electrons or positrons were created in this experiment. The researchers built a model in which ultracold atoms stand in for particles and laser traps stand in for an electric field. The model follows the same rules as the real process, so it lets scientists study how pair production behaves, but it is a simulation, not a direct observation of matter appearing from a real vacuum.

What is an optical lattice?

An optical lattice is a pattern made by overlapping laser beams that can trap atoms in a regular arrangement, like eggs in an egg tray. By adjusting the lasers, researchers can control how tightly the atoms are held and how easily they move between traps. In this experiment, the lattice was a one-dimensional chain, a straight row of traps, with every second trap holding two rubidium atoms and the traps in between left empty.

Why use rubidium atoms?

Rubidium is a popular choice for cold-atom experiments because its atoms can be cooled to extremely low temperatures with lasers and held still enough to photograph individually. In this study, the atoms were the stand-ins for the particles in the theory. Using real atoms that can be seen and controlled one by one is what makes it possible to watch the simulated pair production unfold over time.

What could this research lead to?

In the short term, it gives physicists a controllable way to test the theory of false-vacuum decay and pair production, and to explore what happens when the simulated particles collide. In the longer term, extending the experiment to two dimensions and to other theories could open a window on processes such as string breaking, which are relevant to the physics of quarks inside protons and neutrons. It is basic research, so there is no gadget or product at the end of it, but the understanding it builds feeds into the foundations of physics.

Conclusion

A prediction that has waited decades for a test finally has a laboratory to live in. By arranging ultracold rubidium atoms in a row of laser traps, researchers at the University of Science and Technology of China and their colleagues built a working copy of the Schwinger effect, the process in which a strong electric field turns the energy of the vacuum into particle-antiparticle pairs. They watched the simulated pairs form, measured how the process depended on the particles’ mass and the field’s strength, and saw the wavelike patterns the theory predicts.

The experiment does not claim to have seen the real effect, and that is the point. Some parts of nature are too extreme to recreate directly, so physicists build models that follow the same rules and study those instead. This model works, it can be tuned, and it can be extended. The next steps, collisions between the simulated particles and a move to two dimensions, may reveal even more about a process that sits at the heart of quantum theory. For a phenomenon that has existed only on paper for so long, that is a large step forward.

This article is for general information and education only. It is not legal or financial advice.

Sources

• https://phys.org/news/2026-10-ultracold-atoms-simulate-hard-antimatter.html (Phys.org, 31 October 2026)
• https://arxiv.org/abs/2411.12565 (arXiv, submitted 19 November 2024)
• https://doi.org/10.1103/vhnm-j9bw (Physical Review Letters, 2026)