Rydberg Tweezer Array Demonstrates Kinetically-Induced Bound States of One-Hole-One-Magnon Pairs

The fundamental question of how particles combine to form stable structures underpins much of physics, from molecular formation to the behaviour of exotic materials. Mu Qiao, Romain Martin, and Lukas Homeier, alongside their colleagues, now demonstrate a surprising route to binding, not through attractive forces, but through the motion of particles themselves. The team directly observes these ‘kinetically-induced’ bound states using a Rydberg atom array, simulating the behaviour of interacting particles in frustrated lattices. Their experiments reveal the formation of bound states between ‘holes’ and ‘magnons’, and further demonstrate how these mobile particles shape their magnetic surroundings, inducing order and even unusual correlations. This achievement provides compelling evidence for a novel binding mechanism, potentially offering new insights into unconventional pairing phenomena found in materials like moiré superlattices.

Understanding how particles bind into composite objects is a ubiquitous theme in physics, extending from the formation of molecules to hadrons in quantum chromodynamics and the pairing of charge carriers in superconductors. The formation of bound states usually originates from attractive interactions between particles, but binding can also arise purely from the motion of dopants due to kinetic frustration, a phenomenon offering new insights into the emergence of bound states in various physical systems and expanding the understanding of collective behaviour in many-body physics.

Hole-Magnon Bound States Observed in Rydberg Arrays

Scientists have directly observed kinetically-induced bound states between holes and magnons, utilizing a Rydberg atom array to simulate the behavior of correlated quantum materials. This work provides microscopic characterization of these composite particles, inspired by recent experiments observing kinetic magnetism and superconductivity in moiré systems. The research team realized these systems in both triangular ladders and two-dimensional triangular lattices, allowing for detailed investigation of the underlying physics. Experiments demonstrate the formation of mobile one-hole-one-magnon bound states, where a hole binds to a magnon, creating a composite particle that propagates through the lattice, and further revealed the construction of three-particle one-hole-two-magnon bound states, confirming the binding mechanism through observation of kinetically-induced singlet correlations.

Theoretical calculations show that the binding energy for these states depends on the lattice geometry, with the team focusing on parameters yielding optimal binding. The study also investigated how mobile dopants structure their magnetic environment in a spin-balanced two-dimensional triangular lattice. Results show that a hole induces 120-degree antiferromagnetic order, while a different type of dopant generates in-plane ferromagnetic correlations. These findings demonstrate that kinetic frustration, rather than traditional attractive interactions, drives the formation of these bound states and emergent magnetic order, and measurements confirm that the binding energy for a single hole bound to one magnon, and for a hole bound to two magnons, is dependent on the lattice’s aspect ratio, providing insight into the system’s energetic landscape. This breakthrough delivers a new understanding of pairing mechanisms in correlated materials, potentially informing the development of novel superconducting materials.

Mobile Bound States in Rydberg Atom Arrays

This research demonstrates the first direct observation of kinetically-induced bound states, achieved through a Rydberg atom array simulating a model of interacting particles. Scientists successfully created and imaged mobile one-hole-one-magnon and three-particle one-hole-two-magnon bound states, providing compelling evidence for these composite quasiparticles and revealing the underlying mechanisms responsible for their formation. Measurements of particle correlations indicate that a mobile hole dynamically creates a surrounding “spin bag” of antiferromagnetic correlations, effectively relieving kinetic frustration and fostering attraction between the hole and magnons. Furthermore, the study establishes that the nature of this magnetic environment is dependent on the type of dopant present. In a two-dimensional triangular lattice, a mobile hole induces 120-degree antiferromagnetic order, while a different type of mobile particle generates in-plane ferromagnetic correlations. This programmable quantum simulator offers a powerful platform for bridging theoretical models of strongly correlated systems with condensed matter experiments, potentially advancing understanding of unconventional pairing mechanisms and many-body phenomena driven by kinetic frustration.