  We introduce an exact mapping between the Dirac equation in (1+1)-dimensional
curved spacetime (DCS) and a multiphoton quantum Rabi model (QRM). A background
of a (1+1)-dimensional black hole requires a QRM with one- and two-photon terms
that can be implemented in a trapped ion for the quantum simulation of Dirac
particles in curved spacetime. We illustrate our proposal with a numerical
analysis of the free fall of a Dirac particle into a (1+1)-dimensional black
hole, and find that the Zitterbewegung effect, measurable via the oscillatory
trajectory of the Dirac particle, persists in the presence of gravity. From the
duality between the squeezing term in the multiphoton QRM and the metric
coupling in the DCS, we show that gravity generates squeezing of the Dirac
particle wave function.
