We excite the vacuum of a relativistic theory of bosons coupled to a $U(1)$ gauge field in $1+1$ dimensions (bosonic Schwinger model) out of equilibrium by creating a spatially separated particle-antiparticle pair connected by a string of electric field. During the evolution, we observe a strong confinement of bosons witnessed by the bending of their light cone, reminiscent of what has been observed for the Ising model [Nat. Phys. 13, 246 (2017)]. As a consequence, for the timescales we are able to simulate, the system evades thermalization and generates exotic asymptotic states. These states are made of two disjoint regions, an external deconfined region that seems to thermalize, and an inner core that reveals an area-law saturation of the entanglement entropy.

• Received 7 October 2019
• Revised 9 March 2020
• Accepted 31 March 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.180602