Qubit spin ice

Artificial spin ices are frustrated spin systems that can be engineered, in which fine tuning of geometry and topology has allowed the design and characterization of exotic emergent phenomena at the constituent level. Here, we report a realization of spin ice in a programmable lattice of superconducting qubits in a quantum annealing processor. Unlike conventional artificial spin ice, our system is disordered by both quantum and thermal fluctuations. The ground state is classically described by the ice rule, and we achieved control over a fragile degeneracy point, leading to a Coulomb phase. The ability to pin individual spins allows us to demonstrate Gauss's law for emergent effective monopoles in two dimensions. Finally, we identify a purely entropic screening between emergent monopoles, in the absence of energetic interaction. The demonstrated qubit control lays the groundwork for potential future study of artificial quantum spin liquids and a broad range of spin ice phenomena in various programmable geometries.