  We propose to simulate a Dirac field near an event horizon using ultracold
atoms in an optical lattice. Such a quantum simulator allows for the
observation of the celebrated Unruh effect. Our proposal involves three stages:
(1) preparation of the ground state of a massless 2D Dirac field in Minkowski
spacetime; (2) quench of the optical lattice setup to simulate how an
accelerated observer would view that state; (3) measurement of the local
quantum fluctuation spectra by one-particle excitation spectroscopy in order to
simulate a De Witt detector. According to Unruh's prediction, fluctuations
measured in such a way must be thermal. Moreover, following Takagi's inversion
theorem, they will obey the Bose-Einstein distribution, which will smoothly
transform into the Fermi-Dirac as one of the dimensions of the lattice is
reduced.
