  The Unruh effect predicts a thermal response for an accelerated detector
moving through the vacuum. Here we propose an interferometric scheme to observe
an analogue of the circular Unruh effect using a localized laser coupled to a
Bose-Einstein condensate (BEC). Quantum fluctuations in the condensate are
governed by an effective relativistic field theory, and as demonstrated, the
coupled laser field acts as an effective Unruh-DeWitt detector thereof. The
effective speed of light is lowered by 12 orders of magnitude to the sound
velocity in the BEC. For detectors traveling close to the sound speed,
observation of the Unruh effect in the analogue system becomes experimentally
feasible.
