Scientists have identified a surprising phenomenon in quantum systems that mimics predator-prey dynamics commonly observed in nature.

This newly uncovered behavior, referred to as antagonistic interactions, challenges our classical understanding of physics and Newton’s Third Law, which asserts that every action generates an equal and opposite reaction.

Instead of mutual attraction or repulsion between two groups of particles — as one might expect — the team discovered a one-sided push-and-pull interaction. One group of particles tries to align its quantum spins with another, while the second group resists by attempting to orient its spins in the opposite direction.

“It wasn’t clear if there could be antagonistic interactions in quantum physics since the mathematical formulas typically result in a mutual or reciprocal interaction,” said Tobias Nadolny, a Ph.D. student and one of the authors of the study, in a press release.

Such interactions are not unheard of, especially in biological systems. A classic example is the predator-prey relationship where predators are naturally drawn to their prey, while prey instinctively flee from their pursuers. Similar interactions also occur in metamaterials and certain types of colloids, where forces act asymmetrically to produce complex behaviors.

However, in the realm of quantum mechanics, such interactions had remained purely hypothetical — until now.

Predator-prey dynamics in quantum systems

The research team from the University of Basel used theoretical models to examine a quantum system made up of two distinct groups of particles, each possessing a property called spin — a quantum version of angular momentum.

The particles were exposed to laser light, which supplied energy to the system and enabled precise control over their spin behavior. Among other effects, the laser light synchronized the spin rotations within each group, causing them to rotate in unison — that is, their spins remained in the same phase of their rotation cycle at all times.

The two groups were linked by specialized chiral waveguides — such as specifically designed optical fibers that permitted light to travel in only one direction. These waveguides facilitated communication between the particle groups, but in an asymmetrical manner. One waveguide enabled one group of spins to influence the other, while a second waveguide operated in the opposite direction with different properties, creating an imbalance in how the two groups affected each other.

By tweaking parameters like laser intensity and waveguide properties in their equations, the researchers discovered that the spins of the two groups interacted in a highly unusual way. One group of particles attempted to align its spins with the other group, while the second group resisted by moving its spins into an opposing phase.

This interplay between the two groups of spins created a dynamic reminiscent of predator-prey cycles found in nature, where one group perpetually chases alignment while the other evades it by shifting out of sync.

A quantum time crystal

Another fascinating property of the atomic system is that, under the conditions leading to predator-prey behavior, it exhibited a phenomenon known as a time crystal — a state that periodically repeats itself over time.

“This is similar to a normal crystal, in which the spatial symmetry is spontaneously broken, causing the atoms to arrange themselves in a regular fashion — except that this order does not arise in space, but in time,” explained Brunelli.

Time crystals are an area of significant interest in physics due to their rarity and potential applications in quantum computing, precision measurement, and energy transport. Finding a system that exhibits both time-crystal behavior and predator-prey dynamics makes this discovery particularly exciting.

Real-world implementation

Although this study is primarily theoretical, the researchers are optimistic about its experimental realization. They suggest that the system could be recreated in laboratories using ensembles of ultracold atoms exposed to carefully tuned laser light. Ultracold atoms are already widely used in experiments to simulate exotic quantum phenomena, making this approach feasible with existing technologies.

Moreover, the implications of this discovery go beyond the specific system studied. Antagonistic interactions could potentially exist in a wide range of quantum systems, opening up new avenues for research in quantum mechanics.

“We hope that our results will inspire other researchers to look into quantum systems with antagonistic interactions,” Nadolny concluded.

The findings could also have practical applications in fields like quantum communication and quantum computing. Chiral waveguides, which are central to this system, are already being investigated for their potential in routing quantum information efficiently. Additionally, time crystals might one day serve as robust memory units in quantum devices, thanks to their stable, repeating behavior over time.

Reference: Tobias Nadolny, Christoph Bruder, and Matteo Brunelli, Nonreciprocal Synchronization of Active Quantum Spins, Physical Review X (2025). DOI: 10.1103/PhysRevX.15.011010

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