Worldline-induced transparency

We show that the Unruh response can be interferometrically suppressed or restored in a single Unruh-DeWitt detector whose center of mass is prepared in a coherent superposition of two uniformly accelerated worldlines. The two paths remain physically disjoint; the detector is read out in a basis so that no which-path information is revealed. If the detector’s energy gap is path dependent during the interaction, the branch amplitudes for first-order excitation become operationally indistinguishable and, therefore, add coherently. With appropriate tuning—matching the gap-to-acceleration ratios of the two branches and choosing a single relative phase—the conditional first-order excitation amplitude cancels, while reversing the phase restores the response. We derive these conditions in two complementary formalisms and interpret the mechanism as a relativistic analog of electromagnetically induced transparency, which we term . We also treat finite switching times explicitly and quantify how imperfect matching produces a residual signal, yielding a tolerance window rather than an idealized infinitely sharp condition.