When Constant Driving Does Not Lead to Heating: A Quantum System That Defies Thermalization

In most areas of engineering and physics, repeated driving leads to heating. Mechanical friction raises temperatures, electrical currents generate waste heat, and sustained external forcing usually pushes systems toward thermal equilibrium. This expectation is deeply ingrained in both classical and quantum physics. When energy is injected continuously, especially into systems with many interacting components, that energy is typically absorbed and redistributed as heat.

Guo, Y., Dhar, S., Yang, A., Chen, Z., Yao, H., Horvath, M., Ying, L., Landini, M., & Nägerl, H.-C. (2025). Observation of many-body dynamical localization. Science, 389(6761), 716–719. https://doi.org/10.1126/science.adn8625

A recent experimental study led by Professor Hanns Christoph Nägerl at the University of Innsbruck challenges this assumption. Working with an international team of experimental and theoretical physicists, Nägerl’s group has demonstrated a quantum many body system that remains stable under continuous driving and resists heating altogether. The work provides direct experimental evidence of a phenomenon known as many body dynamical localization, offering new insight into how quantum systems can avoid thermalization.

The experiment focused on a one dimensional gas of ultracold atoms cooled to temperatures just a few nanokelvin above absolute zero. At such low temperatures, quantum effects dominate the behavior of the system, and interactions between particles become strongly correlated. The researchers trapped the atoms in an optical lattice created by laser light, forming a controllable quantum fluid with well defined properties.

To drive the system, the team applied a lattice potential that switched on and off in rapid, periodic pulses. From a classical perspective, this kind of repeated forcing should steadily inject energy into the system. Even in quantum physics, strongly driven many particle systems are generally expected to absorb energy over time, eventually reaching a featureless, high temperature state.

Professor Hanns Christoph Nägerl at the University of Innsbruck stated,

“In this state, quantum coherence and many-body entanglement prevent the system from thermalizing and from showing diffusive behavior, even under sustained external driving. The momentum distribution essentially freezes and retains whatever structure it has.”

Instead, the Innsbruck team observed a different outcome. After an initial adjustment period, the atoms stopped absorbing energy. Measurements showed that the momentum distribution of the particles no longer spread, and the system’s kinetic energy reached a stable plateau. Despite ongoing external driving and strong interparticle interactions, the quantum fluid refused to heat up.

This behavior is described as localization in momentum space. Rather than dispersing energy across higher momentum states, the system becomes dynamically locked into a fixed distribution. The phenomenon, known as many body dynamical localization, is distinct from more familiar forms of localization caused by static disorder. Here, the system remains ordered not because of randomness, but because of coherent quantum dynamics under periodic driving.

According to Nägerl, quantum coherence and entanglement play a central role. The collective quantum state of the atoms prevents energy from spreading in the usual diffusive way. In effect, the system remembers its initial structure and retains it, even while being actively driven.

The result surprised the researchers themselves. Yanliang Guo, the study’s lead author, noted that the initial expectation was rapid heating and disorder. Instead, the atoms behaved in a highly organized manner, maintaining stability where classical intuition predicts chaos.

Theoretical collaborators, including Lei Ying from Zhejiang University, emphasize that this behavior cannot be easily reproduced with classical simulations. Even for systems that appear simple in structure, the number of quantum states and interactions grows rapidly with system size. This makes direct experimental observation essential for understanding driven quantum matter.

To test how robust the effect was, the researchers deliberately disrupted the driving pattern. When small amounts of randomness were introduced into the timing of the pulses, the localization broke down. The momentum distribution began to spread again, and the system resumed absorbing energy. This confirmed that precise periodicity and quantum coherence are critical for maintaining the non heating state.

From an engineering perspective, the findings address a central challenge in emerging quantum technologies. Uncontrolled heating and decoherence remain major obstacles in the development of quantum computers, simulators, and sensors. Understanding how certain quantum systems naturally suppress energy absorption could inform strategies for stabilizing devices under continuous operation.

While the current experiment operates at extreme conditions far from everyday applications, the underlying principles are broadly relevant. Periodically driven systems appear in areas ranging from solid state physics to photonics and cold atom platforms. Insights into how energy flow can be controlled or halted at the quantum level may eventually translate into more robust architectures for quantum hardware.

The study also raises deeper questions about long held assumptions in statistical physics. Thermalization has often been treated as an inevitable outcome of sustained driving. The observation of many body dynamical localization shows that quantum mechanics allows for exceptions, even in interacting systems without disorder.

As experimental techniques continue to improve, similar platforms may be used to explore how far this resistance to heating can be extended. Future work will likely investigate larger systems, different interaction regimes, and potential connections to other non equilibrium phases of quantum matter.

For now, the experiment stands as a clear demonstration that constant driving does not always lead to heating. In carefully prepared quantum systems, coherence and collective behavior can override classical expectations, revealing new regimes of stability that challenge how engineers and physicists think about energy, control, and disorder.