Quantum-Coherent Regime of Programmable Dipolar Spin Ice

TL;DR

This paper demonstrates a programmable quantum spin ice system using superconducting qubits, enabling the study of quantum-coherent dynamics of emergent gauge fields and fractionalized quasiparticles.

Contribution

It introduces a scalable platform for quantum-coherent artificial spin ice with engineered dipolar interactions and real-time dynamics of monopoles and Dirac-string defects.

Findings

Observation of super-diffusive monopole transport with intermediate scaling exponents.

Realization of effective dipolar interactions on large frustrated lattices.

Probing of quantum-coherent dynamics beyond classical relaxation regimes.

Abstract

Frustrated spin-ice systems support emergent gauge fields and fractionalized quasiparticles that act as magnetic monopoles. Although artificial platforms have enabled their direct visualization, access to their quantum-coherent dynamics has remained limited. Here we realize a programmable dipolar square spin-ice model using a superconducting-qubit quantum annealer, providing access to a previously unexplored quantum-coherent regime of artificial spin ice. By implementing a direct one-to-one mapping between lattice spins and physical qubits, together with engineered extended couplings, we realize effective dipolar interactions on frustrated lattices comprising more than 400 vertices. Tuning transverse-field fluctuations enables us to probe the real-time dynamics of Dirac-string defects and interacting monopole plasmas. We observe super-diffusive monopole transport, with scaling exponents intermediate between classical diffusion and ballistic motion, indicating dynamics beyond classical stochastic relaxation and consistent with coherent propagation within an emergent gauge manifold. These results establish programmable quantum spin ice as a scalable platform for investigating fractionalized excitations and emergent gauge dynamics in engineered quantum matter.