Rico, Enrique - Quantum simulation of dynamics in lattice gauge theories Probing Confinement with Superconducting Circuits: From Z₂ String Dynamics to Continuous U(1) Electrodynamics

Rico, Enrique - Quantum simulation of dynamics in lattice gauge theories

Understanding confinement and gauge-field dynamics beyond the reach of classical computation is one of the driving motivations for quantum simulation. I will present two complementary advances using superconducting circuits as a platform for lattice gauge theories (LGTs).

First, I will report on a digital quantum simulation of the Z2-Higgs model in (2+1) dimensions on a superconducting processor with up to 144 qubits and circuit depths reaching 192 two-qubit layers. Matter and gauge fields are mapped directly onto vertex and link qubits of a heavy-hex architecture. Combining error suppression, mitigation, and correction strategies, we observe in real time the string modes of motion of electric flux tubes connecting dynamical charges, providing a direct window into the stringy nature of confinement.

Second, I will introduce a superconducting-circuit architecture for analog quantum simulation of compact U(1) LGT that exploits the intrinsic infinite-dimensional Hilbert space of phase and charge variables. Gauss's law emerges exactly from local charge conservation, without auxiliary stabilizers, penalty terms, or Hilbert-space truncation, while the magnetic plaquette interaction is generated perturbatively through Josephson nonlinearities. Numerical diagonalization confirms the emergence of compact electrodynamics and coherent vortex excitations. Together, these results establish superconducting circuits as a scalable, versatile platform for probing non-perturbative gauge dynamics.