Thermality from a Rindler quench

TL;DR

This paper demonstrates that a sudden spacetime quench in a (1+1)-dimensional model leads to thermal radiation consistent with the Unruh effect, supporting analogue gravity experiments with ultracold atoms.

Contribution

It provides theoretical evidence that a spacetime quench can produce Unruh-like thermality without a late-time horizon, strengthening experimental proposals.

Findings

Late time static observers detect Unruh temperature.

The quench is energetically mild and does not require a horizon.

Thermality persists despite energy injection and absence of a horizon.

Abstract

Ultracold fermionic atoms in an optical lattice, with a sudden position-dependent change (a quench) in the effective dispersion relation, have been proposed by Rodr\'iguez-Laguna et al. as an analogue spacetime test of the Unruh effect. We provide new support for this analogue by analysing a massless scalar field on a $(1+1)$-dimensional continuum spacetime with a similar quench: an early time Minkowski region is joined at a constant time surface, representing the quench, to a late time static region in which left and right asymptotically Rindler domains are connected by a smooth negative curvature bridge. We show that the quench is energetically mild, and late time static observers, modelled as a derivative-coupling Unruh-DeWitt detector, see thermality, in a temperature that equals the Unruh temperature for observers in the asymptotic Rindler domains. The Unruh effect hence prevails, despite the energy injected into the field by the quench and despite the absence of a late time Killing horizon. These results strengthen the motivation to realise the experimental proposal.