Confinement in 1+1D $\mathbb{Z}_2$ Lattice Gauge Theories at Finite Temperature

Abstract: Confinement is a paradigmatic phenomenon of gauge theories, and its understanding lies at the forefront of high-energy physics. Here, we study confinement in a simple one-dimensional $\mathbb{Z}_2$ lattice gauge theory at finite temperature and filling, which is within the reach of current cold-atom and superconducting-qubit platforms. By employing matrix product states (MPS) calculations, we investigate the decay of the finite-temperature Green's function and uncover a smooth crossover between the confined and deconfined regimes. Furthermore, using the Friedel oscillations and string length distributions obtained from snapshots sampled from MPS, both of which are experimentally readily available, we verify that confined mesons remain well-defined at arbitrary finite temperature. This phenomenology is further supported by probing quench dynamics of mesons with exact diagonalization. Our results shed new light on confinement at finite temperature from an experimentally relevant standpoint.