2D Ising Quantum Magnets Demonstrate Collective Cluster Nucleation and Energy-Dependent Steady-State Size

The emergence of collective behaviour in interacting systems presents a fundamental challenge in physics, with implications ranging from superconductivity to the early universe. Philip Osterholz, Fabio Bensch, and Shuanghong Tang, alongside colleagues at the Physikalisches Institut and the Center for Integrated Quantum Science and Technology at the Universität Tübingen, now investigate this phenomenon in a two-dimensional Ising model realised using a novel atomic Rydberg array. Their work reveals a surprising interplay between energy and cluster formation, demonstrating both confined and deconfined regimes governing the nucleation of magnetic domains. This achievement represents a significant advance in simulating complex quantum systems and provides crucial insight into highly collective, non-equilibrium processes relevant to diverse fields including magnetism, glass formation, and even cosmology.

Strongly interacting many-body systems often exhibit collective properties that are intricately linked to their microscopic components. This collectivity governs intriguing ground state properties, such as those found in superconductors, and also influences the non-equilibrium response of quantum systems, extending beyond condensed matter physics into quantum field theories describing the universe. Understanding how emergent collective dynamics arise from fundamental principles, particularly in complex scenarios, remains a central challenge in modern physics.

Rydberg Arrays Simulate Many-Body Physics

Scientists are utilizing arrays of individually controlled Rydberg atoms to simulate and investigate complex many-body physics. Rydberg atoms, created by exciting atoms to very high energy levels, possess exaggerated properties and strong interactions, making them ideal for creating qubits, the building blocks of quantum computation. This allows researchers to explore phenomena that are difficult or impossible to study with other systems. Key techniques include trapping individual atoms with highly focused laser beams, known as optical tweezers, and employing holographic optical tweezers to create complex arrangements in two or three dimensions.

Through these experiments, scientists are observing novel states of matter, including a quantum slush state, and simulating theoretical models like Z2 lattice gauge theories, which describe fundamental forces in particle physics. They are also investigating spin-motion coupling, the interaction between an atom’s internal spin and its motion. This research pushes the boundaries of our understanding of quantum phase transitions and offers potential applications in quantum computing, materials science, and fundamental physics.

Rydberg Array Reveals Cluster Nucleation Dynamics

Scientists have achieved a breakthrough in understanding collective dynamics by observing cluster nucleation in a two-dimensional quantum Ising system realized with an atomic Rydberg array. The work demonstrates coherent control of facilitated Rydberg dynamics in large two-dimensional arrays, paving the way for exploration of complex quantum phenomena. Researchers prepared an array of potassium-39 atoms using optical tweezers, achieving a high degree of control over atomic positions. They then implemented controlled quantum dynamics within a many-atom system, forming a pseudo spin-1/2 subspace using the atomic ground and one Rydberg state.

Experiments reveal a confined regime where the steady-state cluster size directly depends on the applied energy, and a deconfined regime characterized by kinetically constrained dynamics governing cluster nucleation. At the deconfinement point, the energy required to grow an existing cluster matches the energy gained from an external field, resulting in avalanche-like domain growth with strong geometric constraints. These findings demonstrate coherent control over facilitated Rydberg dynamics and open new avenues for studying exotic quantum states, thermalization in strongly constrained systems, and equilibration in glassy systems.

Rydberg Clusters Exhibit Confined and Unconfined Growth

This research details the observation of collective cluster formation following quantum quenches in the two-dimensional transverse field Ising model, a fundamental system in condensed matter physics. Scientists have demonstrated a confined regime where cluster size depends on energy and a deconfined regime characterized by constrained cluster growth and strong interactions. The data reveals large, resonant confined clusters and fast, avalanche-like growth of unconfined clusters, exhibiting a slowdown of dynamics at later times due to the strong interactions between extended clusters, a characteristic feature of glassy dynamics. These findings represent a qualitative advance in simulations using Rydberg arrays and provide new insight into collective, non-equilibrium processes relevant to diverse areas including magnetism and cosmology.

The team’s results present a significant challenge for theoretical modeling and offer valuable benchmark data for advanced numerical methods. Future research directions include investigating the functional dependence of confined cluster energies on the transverse field, studying false vacuum decay dynamics, and exploring the role of long-range interactions. The team also plans to extend these experiments to Kagome lattices to explore lattice gauge theories and further investigate coherent facilitated Rydberg dynamics in two-dimensional arrays.