In the realm of quantum physics, the intuitive expectation is that continuously driving a many-particle system will invariably lead to energy absorption and heating. This presumption mirrors everyday experiences: when an object is repeatedly struck or pushed, its temperature rises, signaling an increase in internal energy. However, groundbreaking experimental findings from the University of Innsbruck challenge this classical view, unveiling a counterintuitive state where a strongly interacting quantum system resists heating despite relentless external driving. This phenomenon, observed for the first time in a complex, many-body quantum fluid, is known as many-body dynamical localization (MBDL).
The experimental team, led by Hanns-Christoph Nägerl at the Department of Experimental Physics, devised a rigorous system composed of ultracold atoms confined to one dimension and cooled to temperatures only nanokelvin above absolute zero. This setup constituted a quantum fluid with strong interatomic interactions, a fertile ground to explore non-equilibrium quantum dynamics. By subjecting these atoms to a rapidly pulsed optical lattice—a periodic potential created by laser light—the researchers imposed a “kicked” landscape designed to impart energy periodically to the system, mimicking classical driving forces expected to increase atomic motion and kinetic energy.
Contrary to the standard hypothesis that external driving should cause the system’s kinetic energy to rise progressively, the atoms demonstrated a strikingly different response. After an initial transient phase marked by some energy absorption and momentum spreading, the distribution of atomic momenta ceased to evolve. The momentum profile essentially froze, and the kinetic energy plateaued, signaling a robust inhibition of energy absorption. This stabilization under constant external forcing heralded the discovery of MBDL, where the quantum system becomes localized in momentum space despite the presence of strong many-body interactions and persistent driving forces.
At the heart of this phenomenon lies the intricate interplay of quantum coherence and many-body entanglement. Unlike classical systems that tend toward thermal equilibrium through diffusion and energy redistribution, this quantum state remains non-ergodic, preserving the structure of its momentum distribution indefinitely. Nägerl eloquently summarizes this: “Quantum coherence and many-body entanglement prevent the system from thermalizing and from showing diffusive behavior, even under sustained external driving.” The result is a quantum fluid that defies classical thermodynamics, exhibiting a dynamic arrest reminiscent of localization but realized in the momentum domain rather than physical space.
One of the experiment’s lead scientists, Yanliang Guo, expressed both surprise and curiosity regarding the orderly momentum dynamics exhibited by the system. Initially expecting chaotic spreading, the team witnessed instead a high degree of order, underscoring the fundamental difference between classical intuition and quantum reality. Complementary theoretical insights from Lei Ying at Zhejiang University highlight the challenge in simulating such complex many-body dynamics on classical computers. “Classical simulations flounder in capturing the full scope of coherence and entanglement driving this stabilization,” Ying notes, emphasizing the vital role of carefully controlled experiments as a bridge toward understanding.
The researchers probed the delicate nature of this phenomenon by introducing controlled noise into the driving sequence, effectively adding randomness or disorder to the timing of the lattice “kicks.” This slight perturbation was sufficient to dismantle the MBDL state, reinstating a diffusive spread of momentum and energy growth akin to classical heating. This sensitivity underscores the pivotal role of quantum coherence: only in its sustained and undisturbed presence does dynamical localization manifest. The destruction of this coherence by disorder rehabilitates the classical expectation of continuous energy absorption and thermalization, highlighting the fragility and exclusivity of the MBDL phase.
This finding carries profound implications beyond fundamental quantum physics. As the quantum information era advances, managing decoherence and heating becomes paramount in the realization of quantum technologies such as quantum computers and simulators. The experimental observation of MBDL imparts a proof of principle that quantum many-body systems can dynamically resist heating and remain stable under continuous driving, a regime previously thought unattainable. These insights open innovative pathways toward engineering quantum devices that harness coherent localization effects to maintain operational integrity and extend coherence times.
Technically, the experiment exploited state-of-the-art laser cooling and optical lattice technologies, pushing the boundaries of ultra-low temperature control and manipulation of quantum fluids. Achieving nanokelvin temperatures minimized thermal fluctuations, ensuring that the quantum effects dominated the system’s evolution. The strong interactions among atoms, tuned via established techniques such as Feshbach resonances or tailored trapping potentials, created a non-trivial many-body environment whose response to periodic driving was far from trivial. The meticulously timed pulse sequences allowed exploration of the parameter space governing the transition between dynamical localization and diffusion.
Beyond validating the existence of MBDL, these results challenge several long-held theoretical assumptions concerning ergodicity and thermalization in driven quantum matter. The observed localization indicates the presence of persistent quantum correlations that effectively shield the system from the chaotic chaotic influence of the external drive. This phenomenon lies parallel to, but distinct from, the well-known Anderson localization observed in disordered static systems, thereby enriching the taxonomy of dynamic phases in quantum many-body physics.
Future research directions inspired by this work include exploring the scalability of MBDL to higher dimensions, diverse particle statistics, and the potential role of disorder and interactions in shaping dynamical phases. Additionally, understanding the interplay between driving frequency, interaction strength, and coherence times could inform the design of novel quantum control protocols for robust quantum state preservation. Collaborative efforts combining advanced theoretical models with sophisticated experimental platforms will be indispensable in uncovering the universal principles underlying many-body dynamical localization.
In summary, the discovery and direct observation of many-body dynamical localization in a strongly interacting, driven quantum fluid mark a major milestone in quantum physics. This phenomenon reveals a new realm where quantum coherence and entanglement safeguard a system against classical thermalization, opening an unprecedented window into nonequilibrium quantum matter. The implications reverberate across fundamental science and quantum technology, promising revolutionary advances in how we harness and control quantum systems in the future.
Subject of Research: Many-body dynamical localization in driven strongly interacting quantum systems
Article Title: Observation of many-body dynamical localization
News Publication Date: 14-Aug-2025
Web References:
References:
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. DOI: 10.1126/science.adn8625
Image Credits: Universität Innsbruck
Keywords
many-body dynamics, dynamical localization, quantum coherence, ultracold atoms, optical lattice, nonequilibrium quantum systems, quantum thermalization, quantum entanglement, momentum space localization, quantum simulation, quantum fluids, driven quantum matter
