Making Something from Nothing: Cold Atoms Model How Particles Appear from Empty Space
In everyday life, empty space is empty. In quantum physics, it is not quite so simple. Quantum theory predicts that a sufficiently strong electric field can convert some of its energy into particles and their antimatter partners — pairs appearing, in effect, from the vacuum. The process is called the Schwinger effect, and in its original form it has never been observed directly, because the electric field needed is far beyond anything that can be produced in a laboratory.
Now researchers have built a controllable laboratory model of the process — not with electric fields and electrons, but with ultracold atoms held in place by laser light. Their experiment is reported in the journal Physical Review Letters by Zi-Hang Zhu and colleagues, led from the University of Science and Technology of China, and was published on 1 October 2026.
A false vacuum made of atoms
The idea the team modelled is called false-vacuum decay. A "false vacuum" is a state that looks stable but is not the lowest-energy state available: it can release energy by transforming into a lower-energy state, in this case by creating particle-antiparticle pairs. "This is an example of 'false vacuum decay,' and in its original form it has never been observed directly," said co-senior author Professor Zhen-Sheng Yuan. "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 model works by analogy. The researchers used laser light to trap ultracold rubidium atoms in a one-dimensional chain — a straight row of tiny optical traps, called an optical lattice. Every second trap contained two atoms, while the traps in between were empty. That arrangement represented the false vacuum.
"We then changed the settings so atoms could hop between neighboring sites in a way that mimics pair creation, tuning the background electric field to control the process," Yuan explained. "A quantum gas microscope imaged the atoms at different times, letting us watch it happen." In the model, an atom moving from a doubly occupied site to a neighbouring site corresponds to a particle-antiparticle pair being created.
The team varied the simulated mass of the particles and the background electric field, and checked how pair production changed. They found that when the simulated particles were heavier, or when the electric field became too dominant relative to other interactions in the model, fewer pairs formed — as expected for false-vacuum decay. They also linked pair production directly to a quantity called the vacuum persistence amplitude, whose squared size gives the probability that the initial vacuum survives, and saw long-lived oscillations in some settings. When the simulated particle mass was set to zero, they observed oscillations resembling the collective excitations predicted by the Schwinger model.
"We were inspired by the Schwinger effect, the prediction that a strong electric field can spontaneously create electron-positron pairs from the vacuum," Yuan said.
A model, not the thing itself
It is important to be clear about what was — and was not — done. The experiment did not create real electrons and positrons from empty space. It created a system of cold atoms whose behaviour follows the same mathematics, so that a process too extreme to observe directly can be studied in a form scientists can control, repeat and tune.
That is the point of a quantum simulator: when nature will not let you turn the dial, build a smaller, colder system that obeys the same rules and turn its dial instead. The team now plans to study what happens when the simulated particles meet, collide and scatter, and to extend the experiment from a one-dimensional chain to two dimensions and to other theories, where richer phenomena such as string breaking may become accessible.
For learners, the lesson is about models. Physicists often cannot experiment on the real thing — a star, the early Universe, or a field stronger than any laboratory can make — so they build a faithful stand-in and test the maths there. Book your first lesson and compare verified physics tutors for help with particles, antimatter and quantum ideas, online, in person or in a group class.
Sources:
- Phys.org, "Ultracold atoms simulate hard-to-observe matter-antimatter pair production", 31 October 2026, reporting Zhu et al., "Probing False Vacuum Decay on a Cold-Atom Gauge-Theory Quantum Simulator", Physical Review Letters 137, 141601 (2026), DOI: 10.1103/vhnm-j9bw: https://phys.org/news/2026-10-ultracold-atoms-simulate-hard-antimatter.html
- American Physical Society, Physics, "Simulating Particle Creation with Cold Atoms", 1 October 2026, summarising Zhu et al., Physical Review Letters 137, 141601 (2026): https://physics.aps.org/articles/v19/s131