Confinement in a $${{\mathbb{Z}}}_{2}$$ lattice gauge theory on a quantum computer

Abstract

Gauge theories describe the fundamental forces in the standard model of particle physics and play an important role in condensed-matter physics. The constituents of gauge theories, for example, charged matter and electric gauge field, are governed by local gauge constraints, which lead to key phenomena such as the confinement of particles that are not fully understood. In this context, quantum simulators may address questions that are challenging for classical methods. Although engineering gauge constraints is highly demanding, recent advances in quantum computing are beginning to enable digital quantum simulations of gauge theories. Here we simulate confinement dynamics in a $${{\mathbb{Z}}}_{2}$$ lattice gauge theory on a superconducting quantum processor. Tuning a term that couples only to the electric field produces confinement of charges, a manifestation of the tight bond that the gauge constraint generates between both. Moreover, we show how a modification of the gauge constraint from $${{\mathbb{Z}}}_{2}$$ towards U(1) symmetry freezes the system dynamics. Our work illustrates the restriction that the underlying gauge constraint imposes on the dynamics of a lattice gauge theory, showcases how gauge constraints can be modified and protected, and promotes the study of other models governed by multibody interactions. Gauge theories host important phenomena such as confinement that are difficult to study theoretically. Advances in quantum computers have now made it possible to perform digital quantum simulations of confinement dynamics in a gauge theory.