Typically, adding energy to a system makes it hotter. But last year, scientists demonstrated that quantum systems don’t always follow those patterns, finding a quantum gas that essentially refuses to heat up.
After some investigating, a closely related team identified the microscopic origin of this seemingly nonsensical behavior, reporting its findings in a recent paper published in Physical Review Letters. For the study, the researchers, an international team based in China and Austria, devised a mathematical framework that allowed them to track the individual interactions within the system. As a result, they discovered that in this particular structure, strongly interacting atoms reshape how the system behaves within the local lattices.
Quantum kicks
Key to this finding is a phenomenon called dynamical localization, or an “unexpected halt in energy growth” for single particles exposed to periodic “kicks” of energy in quantum systems, according to the paper.
That “starkly contrasts our everyday experience, which tells us that driven systems generally thermalize to infinite temperatures,” the study noted. Physicists wondered if similar behavior could be observed in more complex systems, since singular particles were relatively easy to control, anyway.
The freeze
This was what the 2025 experiment set out to demonstrate and, impressively, succeeded in doing so. For the previous study, the team created a one-dimensional quantum fluid of strongly interacting atoms, cooling it down to near absolute zero. Then they gave the atoms periodic “kicks” with laser light to see how the system would change.
As expected, the atoms did bounce around at first, but their momentum began to slow and eventually plateaued as the system no longer absorbed energy—and therefore stopped heating up. It had “localized in momentum space,” the researchers explained in a statement on the 2025 findings.
“We had initially expected that the atoms would start flying all around. Instead, they behaved in an amazingly orderly manner,” Yanliang Guo, the 2025 study’s lead author and a co-author of the 2026 study, said in the statement. “This goes against our classical intuition and reveals a remarkable stability rooted in quantum mechanics.”
Finding the breakdown
In 2025, Guo stressed the importance of developing models to fully test and understand these systems—hence the latest study. The new mathematical model mapped the relationship between the strength of the interactions between particles and the amplitude of the system’s momentum. According to the paper, at a certain point the external kicks of energy lead to a “breakdown” in how much energy the local system is willing to accept.
While fascinating, the latest study, unlike the team’s previous work from 2025, is largely theoretical. This is something the team points out as well; the math checks out, but ideally, the researchers hope to soon take things to the experimental level. What’s more, their calculations suggest that the model could be extended to other quantum systems known to occasionally leave thermodynamics in the dust.
For now, the findings leave more questions unanswered. As the team asks in the paper, “Is there a critical kick strength or interaction strength for an arbitrary number of particles? And is localization stable at finite interaction strength in the thermodynamic limit?”
