Circular-Motion Fulling-Davies-Unruh Effect in Coupled Annular Josephson Junctions

We propose an experimentally feasible approach for observing the Fulling-Davies-Unruh effect in circular motions using a novel detector based on the thermally activated decay of metastable bunched fluxon-antifluxon pairs in coupled annular Josephson junctions. The uniform circular motion of fluxon pairs acting as detectors under relativistic velocities and small radii produces high acceleration, making an effective Unruh temperature on the order of 1 K observable with existing technologies. In addition, the newly designed detector delivers highly sensitive temperature measurements, offering a promising avenue for experimentally probing the nontrivial properties of the quantum vacuum. Numerical simulations confirm a clear acceleration-dependent temperature providing compelling evidence for the Fulling-Davies-Unruh effect.