Experimental Observation of Curved Light-Cones in a Quantum Field Simulator

TL;DR

This paper experimentally observes how correlations propagate along curved light-cones in a quantum field simulator, revealing effects of inhomogeneity and boundary reflections consistent with theoretical models.

Contribution

It demonstrates the first experimental observation of curved light-cones in a quantum field simulator with inhomogeneous density profiles.

Findings

Correlations propagate along sharp light-cone fronts.

Inhomogeneous density causes curvature in the propagation fronts.

Propagation fronts reflect at system boundaries.

Abstract

We investigate signal propagation in a quantum field simulator of the Klein-Gordon model realized by two strongly coupled parallel one-dimensional quasi-condensates. By measuring local phononic fields after a quench, we observe the propagation of correlations along sharp light-cone fronts. If the local atomic density is inhomogeneous, these propagation fronts are curved. For sharp edges, the propagation fronts are reflected at the system's boundaries. By extracting the space-dependent variation of the front velocity from the data, we find agreement with theoretical predictions based on curved geodesics of an inhomogeneous metric. This work extends the range of quantum simulations of non-equilibrium field dynamics in general spacetime metrics.