A tabletop ring of atoms brings the universe's doomsday vacuum collapse into the lab

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Physicists in China have simulated the effect of "false vacuum decay": a phenomenon believed to play out constantly in the seemingly empty expanses of space, and which one theory even suggests could bring an abrupt end to the entire universe. In a paper published in Physical Review Letters, Yu-Xin Chao and colleagues at Tsinghua University, Beijing, mimicked the effect using a simple tabletop experiment.

False vacuum decay

For now, quantum field theory is our most accurate framework for fundamental physics below the scale at which gravity becomes important. It predicts that there is no such thing as a perfect vacuum: while a given space may appear entirely empty, the theory suggests that it is actually just the lowest-energy state of a continuous quantum field.

Since a quantum field can possess multiple local minima energy, this means that a seemingly stable local ground state may not be the most stable state possible for the field as a whole—it is simply separated from a lower-energy, more stable state by an energy barrier, much as a valley may be separated from a deeper valley by a high mountain ridge.

This "metastable" state, known as a "false" vacuum, could overcome the barrier separating it from the "true" vacuum via quantum tunneling. This allows it to pass straight through the barrier without any energy input, much like a tunnel passing under a mountain between two valleys.

In the 1970s, American theorist Sidney Coleman suggested that the entire observable universe could exist in such a false vacuum. If so, a false vacuum decay would cause it to instantaneously collapse into a true vacuum.

"While we cannot test this theory on a universal scale, the recent development of highly controllable quantum simulators allows us to recreate and study these dramatic tunneling events in tabletop experiments," explains co-author Meng Khoon Tey.

Programmable Rydberg ring

To bridge this experimental gap, Chao's team looked to the properties of Rydberg atoms, whose outermost electrons have been excited to extremely high energy levels. On atomic scales, these electrons occupy orbits extremely distant from their host nuclei, making them far more responsive to external fields. As a result, they are especially well-suited as a basis for controllable quantum simulations.

In this case, the researchers arranged a group of mutually repulsive Rydberg atoms into a ring. Within the structure, the spin state of each atom preferred to align itself in the opposite direction to that of its two neighbors, creating an orderly alternating pattern between "up" and "down" states. Due to the symmetry of the system, both possible alternating patterns ("up-down-up-down" and "down-up-down-up") possessed identical energies, making them equally stable.

To simulate a false vacuum, the researchers then broke this symmetry deliberately using a laser, so that the ring could exist in two possible patterns with slightly differing energy states—mimicking true and false vacuum states.

"By illuminating alternating atoms with site-selective laser beams, we engineered a custom energy landscape with distinct 'false' and 'true' vacuum states, allowing us to watch the quantum tunneling process unfold in real-time," Tey explains.

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Exponential decay

As they observed the process, Chao's team measured the decay in the alternating spin pattern, as quantified by an "order parameter." Just as predicted by quantum field theory, they found that the decay rate increased (approximately exponentially) as the symmetry-breaking field grew stronger—so that the stronger the field, the faster the simulated vacuum state decayed.

This directly mirrored the mechanism of quantum bubble nucleation: to transition to the true vacuum, the system must form a "bubble": a locally transformed region of the true vacuum large enough to compensate for the energy to break the initial pattern. A stronger symmetry-breaking field reduces the required size of this bubble, meaning fewer atoms are needed to collectively tunnel. In turn, the decay process becomes more likely.

Beyond the short-term dynamics resembling false vacuum decay, the team also explored long-term behavior, finding that decay was dramatically enhanced at certain field strengths: a feature unique to discrete quantum systems that has no counterpart in continuous quantum fields. This distinction opens the door to studying a richer range of physics than classical false vacuum decay alone can offer.

"Our experiment has replicated the predicted false vacuum decay in a fairly simple tabletop experiment," Tey says. "This provides a stepping stone to exploring how the many-body tunneling dynamics are affected by its lattice geometry, and the ubiquitous long-range interactions between atoms."

Written for you by our author Sam Jarman, edited by Sadie Harley, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

Publication details

Yu-Xin Chao et al, Probing False Vacuum Decay and Bubble Nucleation in a Rydberg Atom Array, Physical Review Letters (2026). DOI: 10.1103/kqzq-fnr4. On arXiv: DOI: 10.48550/arxiv.2512.04637

Journal information: Physical Review Letters , arXiv

Key concepts

Cold atoms & matter wavesOptics & lasersQuantum field theoryAtomic systemsQuantum many-body systems

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