Meson spectroscopy of exotic symmetries of Ising criticality in Rydberg atom arrays

TL;DR

This study uses Rydberg atom arrays to explore emergent symmetries and confinement phenomena in quantum critical Ising models, providing experimental evidence for theoretical predictions of exotic symmetry groups.

Contribution

First experimental observation of confinement and bound states in Rydberg atom arrays consistent with $E_8$ and $ ext{D}_8^{(1)}$ symmetries at criticality.

Findings

Identified mass spectra consistent with $E_8$ symmetry in single-chain configurations.

Reported signatures of confinement into bound states in weakly coupled ladder configurations.

Demonstrated Rydberg platforms as effective tools for studying emergent symmetries in quantum many-body systems.

Abstract

The Ising model serves as a canonical platform for exploring emergent symmetry in quantum critical systems. The critical point of the 1D Ising chain is described by a conformal Ising field theory, which remains integrable in the presence of a magnetic perturbation, leading to massive particles associated with the exceptional Lie algebra $E_8$. Weakly coupling two Ising chains into a ladder breaks this integrability and is predicted to confine the elementary excitations of each chain into a richer spectrum of bound states organized by a $\mathcal{D}^{(1)}_8$ symmetry. Experimental signatures of $E_8$ excitations have arguably been observed in scattering studies of the spin chain material CoNb$_2$O$_6$, but direct evidence of confinement driven by inter-chain coupling has remained elusive. Here, we probe these emergent symmetries in a Rydberg atom quantum processing unit, leveraging its tunable geometry to realize both chain and ladder configurations. We identify mass spectra consistent with $E_8$ at the single-chain critical point and, in the weakly coupled ladder, report the first signatures of confinement of Ising excitations into the bound-state spectrum predicted by $\mathcal{D}^{(1)}_8$ symmetry. Our results demonstrate the power of Rydberg platforms for investigating symmetry emergence in quantum many-body systems and provide a direct window into the interplay of confinement, geometry, and criticality.